Ignore the large baby bump under her expensive-looking floaty boho top and Thomasina Miers could be any graduate talking excitedly about her year abroad.

In fact it's 17 years since the long-limbed, tanned and, when we meet, pregnant, 2005 Masterchef winner discovered South American cuisine during her gap year. She's gone on to open four Wahaca restaurants, write multiple books and now star in TV show Mexican Food Made Simple.

News Shopper: Mexican Food Made Simple, by Thomasina Miers, published by Hodder & Stoughton, priced £20. PA Photo/Hodder & Stoughton

"I was a VAT consultant for nine months of my gap year and utterly miserable," she says in excitable, plummy, schoolgirl tones. "So I went to Mexico where I travelled around, drinking a lot of tequila, dancing and eating."

Miers, who's just given birth to a baby girl, admits she was a "very arrogant 18-year-old".

"I had been cooking since I was six and thought I knew everything. But on the third night, I went to a party where this woman cooked a spread and I didn't recognise any of the flavours - or chillies - or anything.

"I couldn't believe I'd never heard of this food before," she finishes, twisting her curly dark hair around her fingers.

But like so many childhood dreams, Miers assumed her passion for food was just a bit of fun.

"By 2003 I had tried all these different careers and was miserable because I couldn't find anything I could stick at," she explains honestly.

"I did some marketing, advertising and modelling. In fact I was literally going down the catwalk in a bikini helping out a mate, when I met Clarissa Dickson Wright.

"In those days I didn't think cooking could be a career. She really opened my eyes and sent me off to cookery school."

With a qualification in her pocket, Miers ducked straight back to Mexico, beginning a proper exploration of their cuisine, and even opened a cocktail bar.

"As you travel round Mexico, you'll find different ingredients every 10 miles. Each time I go back I learn so much more.

"The majority of Mexicans live below the poverty line. They slow-cook their meat to get the most out of the flavour, using herbs like oregano, thyme and bay leaves. Then they use fresh herbs on top to get the fresh notes and chillies to add a lovely light heat. Not all chillies are burning hot though, some are sweet, some smoky and others have tobacco notes."

News Shopper: Thomasina Miers. PA Photo/Handout

After a blissful year of eating, Miers returned, as a student poor as ever, and signed up for Masterchef as a last resort.

"When you see the chefs on television and they talk about sacrificing so much, you think, 'Well it's just good fun isn't it?'.

"But actually it involves weeks not earning and paying the mortgage, so it is a massive sacrifice but it can turn your life around.

"I was desperate and essentially unemployed anyway, so I had nothing really to give up.

"I remember rocking up to the studio on the first day feeling a bit cocky, thinking it was a bit of a joke and then seeing Greg [Wallace] and John [Torode] being polite and mashing potatoes in these massive pans. I thought, 'Oh my God' and started to shake."

Luckily, her South American-inspired food wowed the critical pair, although it took a while to convert her win into cash.

"It was really difficult. The show comes out five months after you film it. So having won a competition that's never been on television, you don't know what to do!"

After landing a job with a restaurant kitchen, she quickly moved on to food writing, before establishing her own chain of restaurants.

In her first TV series, Miers sets off to the markets of Mexico City in search of the perfect traditional dishes such as tacos, tamales and tastadas, before whipping up easy versions for viewers.

"The thing about Masterchef is that it's very 'cheffy', whereas I love produce.

"What's so great about Mexico is that you get people on every income passionate about food and taking care of what they put in their mouths and feed their children.

"Why eat bad food when you can eat good food? It's got nothing to do with money."

As she nods happily, leaning against a bar stool in her colourful restaurant, it's easy to believe viewers will also be carried away by her enthusiasm.

Here are three recipes from Mexican Food Made Simple to try...

Coconut ceviche

(Serves 4)

News Shopper: Coconut Ceviche. PA Photo/Tara Fisher

2-3 plum tomatoes
225g sea bass, skinned and diced into 1cm cubes
Juice of 5-6 limes
4tbsp coconut milk
1tbsp olive oil
A pinch of sea salt
½ small red onion, finely diced
1 clove of garlic, finely chopped
1 habanero (Scotch bonnet) chilli, finely diced
A large handful of coriander leaves, chopped
Chopped coriander leaves
4-5 radishes, finely sliced
½ avocado, peeled, stoned, roughly diced and tossed in the juice of ½ lime
Totopos (tortilla chips)

Cover the tomatoes with boiling water and count to 20. Drain and pierce them with a knife so the skins slip off easily. Deseed and dice the tomatoes into 1cm cubes.

Place the fish in a glass bowl, add the lime juice, coconut milk, olive oil, salt, onion, garlic and chilli. Cover and refrigerate for at least an hour for a light marinade, or 4 hours in total if you want the fish to be completely 'cooked'. The flesh of the bass will turn from translucent to opaque and white when it's completely cooked.

Drain the fish of the marinade, keeping it aside. Add the tomato and coriander to the fish and gently mix together, adding some of the marinade back if it looks dry. Spoon the ceviche onto small starter plates and sprinkle over the chopped coriander, sliced radishes and diced avocado. Hand out tortilla chips to scoop up and eat the ceviche.

Chorizo, potato & thyme quesadillas

(Serves 4 large quesadillas)

News Shopper: Chorizo, Potato & Thyme Quesadillas, taken from Mexican Food Made Simple by Thomasina Miers. PA Photo/Tara Fisher

350g potatoes
½ onion, finely chopped
1 clove of garlic, chopped
200g chorizo cooking sausage, chopped
A small bunch of thyme, chopped
Sea salt and black pepper
4 large flour or corn tortillas
400g cheese, grated
Olive oil

Cut the potatoes in equal-size chunks and cook until tender. Leave them to cool a little and then dice into 1cm squares. Cook the onion until soft, add the garlic and cook for a further three minutes. Mix in the chorizo and potato, turn up the heat and fry for another five minutes. Mix in the thyme and season. Assemble the rest of the quesadilla ingredients.

Spread a quarter of the chorizo mixture on one half of a tortilla and sprinkle with a fistful of cheese.

Fold the tortilla over so that you have a half moon. Brush it with a little olive oil (so the tortilla doesn't stick to the pan) and place in a hot, dry frying pan or griddle and cook until golden and crisp. Repeat with the remaining tortillas.

Cut into wedges and serve with your favourite table salsa.

Mango & strawberry salad

(Serves 6)

News Shopper: Mango & Strawberry Salad. PA Photo/Tara Fisher

3 ripe mangoes (the Pakistani honey mangoes are delicious)
A large punnet of strawberries
1-2tbsp unrefined caster sugar
Juice of 1 lime
A few generous splashes of tequila
A large handful of mint leaves, roughly chopped

Peel the mangoes, remove the stones, cut the flesh into rough chunks and place into a salad bowl. Hull the strawberries and cut in half (or thirds if they're very large), adding to the mangoes as you go.

Sprinkle over the sugar, lime juice and tequila and let sit for at least 10 minutes in the fridge. Bring out before serving to allow the salad to get to room temperature and scatter over the mint leaves.

This looks very pretty served in glass pudding bowls or tumblers.

:: Mexican Food Made Simple is currently on Tuesdays on Channel 5. The book by Thomasina Miers is published by Hodder & Stoughton, priced £20