“It’s one of the most biodiverse countries in the world and the foundations of the diet are corn, beans, the courgette plant, tomatoes, chilies and wild herbs”, says Miers, 46. Mexico has around 50,000 native plant species (by some estimates), with some 200 varieties of chilli alone, compared with the UK and Ireland’s 1,500 or so.

Protein often came from moles (a traditional type of sauce made from beans), “enriched with lots of ground seeds”, adds Miers. “The authentic way [to make it] is often very complicated, with 37 ingredients.” (But don’t worry, she has recipes with just eight).

“A lot of the housewives in Mexico make their own vinegars at home out of guava, pineapple or apple,” she notes.

The idea of packing your diet with a rainbow of vegetables is very much the focus of her new book, Meat-Free Mexican. “I think we’re really beginning to think about food as medicine much more these days, which I think is completely right”, she says. Plus, “people are looking at eating less meat anyway, because environmentally, how much meat we’re eating is a total catastrophe”.

Miers – who won MasterChef in 2005 and is the brains behind the hugely successful Wahaca chain of Mexican restaurants (where 50% of the menus are now vegetarian) – says: “I love that ancient Mexican food and the modern way we’re all kind of starting to eat, feel very in synergy together.”

From plant-based versions of Mexican classics, like beetroot ceviche, celeriac and chard enchiladas, chickpea rancheros and cauliflower tacos, to vegetable dishes that celebrate Mexican spices and flavourings, like chipotle-tamarind baked sweet potato gratin and baked polenta with veracruzan sauce, her eighth cookbook (and her third Mexican-focussed) is, like all of her recipes, for “people who are busy”. So although some are longer, it all feels do-able for the time-starved generation.

“I’m a working mum,” she says, “I’m perpetually short of time. For me, food has got to fit into busy lives.” There’s even a place for Tex Mex, with her ‘chile non carne’ – a handy family favourite.

“Some people will spend two days making a recipe and that’s great – and I used to do that, before kids,” Miers adds with a laugh. “But not everyone has that time."

“What I love about Mexican food is you can spend a weekend making your own flour tortillas (I love making flour tortillas from scratch because they taste so good and they’re really easy). Equally, if it’s midweek, I’m just going buy some and that’s fine.”

The mum-of-three first fell in love with the food of Mexico while travelling there between school and university. Before that, she’d always thought of Mexican cuisine as American-style Tex-Mex – but eating her way around the valleys of Oaxaca, the coast of Campeche and the rainforests of Veracruz, falling in love with “the colour, the vibrancy, the creativity” soon opened her eyes. She later returned to live in Mexico City and opened her first Wahaca restaurant in London’s Covent Garden in 2007 – now there are 13 across the UK.

“When I look back now, the first thing I think about are the salsas on the tables”, she says, reflecting on the early travels that inspired her career. “They’re made fresh every day, they’re different in every cantina that you go to or every street food [stall], every single cook has their own special recipes. They are all packed full of vitamins and minerals and goodness, they’re fresh and zingy.”

Surprisingly, it reminded her of home. “My mother always used to make homemade mayonnaise, barbecue sauces, ketchup bases, mint sauce and horseradish cream, so I felt like the Mexican way of eating with salsas dolloped on food was actually quite like the way we eat in Britain – we love to dollop sauces onto food.

“I love layering flavour on to things. The salsas, the chilli oils, the moles – for me it’s not just levels of goodness and nutrition but flavour and texture and colour. And it brings all the food alive.”

Guacamole – and avocados generally – may be a staple in Mexico, but their environmental footprint (for a fruit) has weighed heavily on Miers’ mind. It’s why Wahaca put an alternative guacamole on their menus last year – ‘wahacamole’ made from British fava beans.

“Avocados are lovely – but as treats,” she says. “Anything that grows within 50 or 100 miles of you is a great staple to eat because there’s less of an impact. Exotic fruit is great for special occasions, but having them as a mainstay of your diet is going to be bad for the environment.”

“I’m a cook,” she says. “I wouldn’t be without my coriander seeds and my star anise and my cinnamon stick. But yes, they come from the other side of the world – it’s about putting it all in proportion.”

Impact on the environment is the main reason Miers is flexitarian. “I generally eat meat if I’m in control of where it comes from. Factory farmed meat is a big no-no for me, in terms of welfare and emissions.”

“Beef, I eat probably four times a year. We buy chicken from the market once every few weeks, because we buy expensive ones that are fed on grass and not grain that’s been grown in the Amazon basin.”

“I think that for me is the key – is the animal I’m eating impacting the rainforest in Brazil? Well, if they are, I don’t want a piece of it, personally.”

For the future of our planet and for our kids, we have to eat less meat, she urges. “We’re still opening factory farms, and the government’s talking about reducing carbon targets”, she sighs. Runoff from the huge amount of animal waste at factory farms often pollutes nearby rivers, according to Food Print – “so I’d rather not have chicken if it’s from an industrial chicken farm close to a river”, says Miers.

We’ve got too used to eating whatever we want, at whatever cost to the planet, she suggests. But we can still enjoy a lot of food responsibly. “Cooking should be fun, it should be about feeding the people you love, it should be about pleasure, but within limits. It’s not about having whatever you want, whenever you want, but it is about flavour and taste, and joy”, says Miers.

“Why should we eat meat all the time at the expense of species decline and insect extinction and the total destruction of our soil? For the future of mankind, apart from anything else, it doesn’t seem to make sense to me.”

Blistered green bean tacos with tomato pico and toasted almonds

Ingredients:

(Serves 4)

75g flaked almonds

500g green beans, topped

2tbsp olive oil

3 garlic cloves, sliced

3tbsp capers (the bigger the better)

Sea salt

For the small corn tortillas (makes 12)

800g masa harina flour

1tsp salt

600ml warm water

Vegetable oil, for frying

(You’ll also need a clean plastic bag torn into two halves, two sheets of parchment paper and a tortilla press or a rolling pin)

For the tomato pico:

6 very ripe plum or cherry tomatoes

Small handful of coriander

1 small red onion, very finely diced

1–2 green chillies, preferably jalapeños, very finely chopped

1tbsp extra-virgin olive oil

Juice of 1–2 limes

1tsp sea salt

1tsp soft brown sugar

Salt and pepper

To serve:

Crumbled feta (optional)

Sliced avocado (optional)

Method

1. First make the pico: cut the tomatoes into quarters and scoop out the watery insides (you can keep them and use them in a vinaigrette or in a soup). Dice the flesh.

2. Roughly chop the coriander leaves and finely chop the stalks and stir into the tomatoes with the onion, chillies, oil, half the lime juice, the salt and sugar. Check the flavour and add more salt, pepper or lime juice if you think the salsa needs it. Leave to marinate for at least 20 minutes.

3. To make the tortillas, combine the dry ingredients in a bowl, then gradually stir in the warm water until a dough begins to form. Knead in the bowl for two to three minutes until smooth, then cover with a dish towel and rest for 30 minutes. You want it to feel springy and firm, similar to the texture of play-doh. If the dough feels too wet and is sticking to your hands, add a few tablespoons of flour. If it feels too dry, add an extra tablespoon or two of warm water.

4. Divide into 30g balls and place on a plate, covered with a damp cloth to stop them sticking. Put one half of the plastic or parchment onto the tortilla press or worktop and place your first ball in the middle. With two fingers, gently press down on the tortilla ball to squash it into a thickish disc. Cover with the second sheet of plastic, to stop the masa from tearing or sticking, and press or roll out into a thin tortilla, about 3mm thick.

5. Peel away the top plastic, then pick up the sheet that the tortilla is on and flip it face down onto the opened palm of your hand, tortilla to skin. Peel away the plastic top and turn out the tortilla into a lightly oiled pan.

6. Cook on one side for 20–30 seconds, until the tortilla starts to look cooked, with lovely browned spots of toasting. If you are lucky it may even puff up! Turn and cook for another 30 seconds, then turn once more. Remove from the pan and keep wrapped up in a dish towel in a warm oven.

7. Put your largest frying pan over a medium heat and when hot, toast the almonds, shaking the pan until they are mostly a lighter shade of caramel. Put aside to cool.

8. Turn the heat up under the pan and add the beans in two batches. Sauté each batch for four to five minutes until they are looking a little blackened all over and starting to blister. Season with sea salt and remove from the pan into a warm bowl. Now pour in the olive oil and add the garlic and drained capers (watch for spitting if they are still a little wet). Cook for a couple of minutes or so until the garlic is golden and empty onto the beans.

9. Pile the beans into the tortillas and top with the garlic and capers, spooning over heaped spoonfuls of the tomato salsa. Sprinkle with the almonds and crumbled feta and avocado, if using, then munch with gusto.

Beetroot Ceviche with tarragon, blood orange and avocado ‘crema’ recipe

Ingredients:

(Serves 6 as a starter or fewer as part of a light meal)

4 medium beetroot

2.5tbsp olive oil

30g sunflower seeds

1 avocado

1.5tbsp lime juice

2tbsp chopped coriander stalks plus small handful of roughly chopped coriander leaves

3 radishes

2 spring onions, finely chopped

Small handful of roughly chopped tarragon leaves

Fine sea salt

Cress or pea shoots, to garnish (optional)

For the dressing:

1 Scotch bonnet chilli (or a bird’s eye)

1 small garlic clove, unpeeled

1/4 tsp cumin seeds

1tsp caster sugar

2tbsp lime juice

7tbsp extra-virgin olive oil

Juice of 1/2 orange (blood or otherwise)

Salt

Method

1. Preheat the oven to 200°C/180°C fan/400°F/gas 6.

2. Rub the beetroot with one tablespoon of the olive oil, followed by a little fine sea salt, pop into a baking tin and cover with foil. Roast for one hour or until tender when pierced with a knife.

3. Toast the sunflower seeds in a dry frying pan (skillet) until golden. Remove and set aside. Meanwhile, to make the dressing, put the chilli and garlic in the dry frying pan over a medium–high heat and toast on both sides until blackened all over, about five to seven minutes. Toast the cumin seeds for 30 seconds in the same pan.

4. De-seed the chilli, cut into quarters and peel the garlic. Pound a quarter of the chilli to a paste in a pestle with the garlic and several pinches of salt, the cumin and the sugar. Work in the lime juice and finally pour in the olive oil and orange juice and stir to combine.

5. Blitz the avocado with the lime juice, one-and-a-half tablespoons of water and the remaining oil. Add the coriander stalks and two to three large pinches of salt and blitz again to a smooth, thick cream.

6. When the beetroot is cooked, allow to cool for five minutes, then pop on a pair of washing-up gloves and rub away the beetroots’ skin. Slice into rounds about 3mm, preferably with a mandolin. Arrange them in overlapping circles on a large serving plate and dress with the dressing while still warm.

7. Slice the radishes to paper-thin discs (use the mandolin if you have it). Scatter over the spring onions, coriander and tarragon leaves and the seeds and dot with the avocado cream. Serve at once with the cress or pea shoots.

Mango and chocolate paletas recipes

Ingredients:

(Makes 10-12)

For the mango dipped in chili salt version:

2 small ripe mangoes (220g)

Zest and juice of 1 lime (40ml)

2–3tbsp light agave nectar

For the chilli-lime salt:

10g piquin chillies or Urfa chilli flakes

10g fine sea salt

100g caster sugar

Zest of 1 lime

For the Mexican chocolate version:

400ml almond or whole milk

Few pinches of ground cinnamon

55g dark chocolate, chopped

55g milk chocolate, chopped

1–2tbsp golden syrup

90g white chocolate

50g almonds (flaked/slivered)

Method

1. To make the mango paletas, skin and stone the mangoes and add the flesh (and as much juice as you can) into a blender. Add the lime zest and juice and agave with 300ml water and blend to combine.

2. Taste the mixture and add more agave if needed, remembering to sweeten more than you think necessary, as much of the sweetness disappears once the lollies are frozen. Pour into lolly moulds and freeze for at least eight hours.

3. To make the chili salt, blitz the chillies with the salt in a spice grinder or small food processor, then stir in the sugar and lime zest. Serve the mango paleta dipped into the chilli-lime-salt.

4. To make the Mexican chocolate paleta, add the milk to a heavy-bottomed saucepan and warm over a low heat with the cinnamon and golden syrup. Take the milk off the heat and stir through the chocolate until completely melted. Leave to cool and then pour into lolly moulds. Freeze for at least eight hours.

5. To decorate, melt the white chocolate and toast the almonds. Drizzle the paletas with the white chocolate and sprinkle with the almonds.

Meat-free Mexican: Vibrant Vegetarian Recipes by Thomasina Miers is published by Hodder & Stoughton. Available now.