Portobello Mushroom Fajita

While the mushrooms cook, halve, peel and thinly slice the red onion. Peel and grate the garlic (or use a garlic press). Trim the root from the baby gem lettuce then halve lengthways. Thinly slice widthways. Drain and rinse the black beans in a sieve.

Roughly chop the tomatoes into very small pieces. Place in a bowl, making sure you don't leave behind any of the delicious tomato juices. Add a drizzle of olive oil and squeeze in the sriracha. TIP: Be careful it's hot, just add a little to start. Season with salt and pepper to taste and set to one side. Grate the Cheddar cheese and set aside.

Heat a drizzle of oil in a large frying pan over medium-high heat. Once hot, add the onion. Cook until softened and lightly coloured, 5-6 mins, then stir in the garlic and Mexican spice mix (don't add it all if you don’t like too much heat!). Cook for 1 more minute, then add the beans, water (see ingredients for amount) and stock powder to the pan. Stir everything together and cook until the beans begin to break down, 5-6 mins.

After 5-6 mins, break up half of the beans with a potato masher (or the back of a fork) and continue simmering until the beans have thickened, 3-5 mins. Remove the pan from the heat and season with salt and pepper to taste. Place the tortillas onto the middle shelf of the oven to warm through, 1-2 mins.