Warm the olive oil in a large frying pan over a medium-high heat. Add the diced red onion and cook for 3 to 4 minutes, until it turns translucent and glossy and you can smell that sweet, mellow onion aroma rising from the pan.

Add the garlic and cook for just 30 seconds. It should smell fragrant and nutty, but watch it closely — the moment it starts to brown at the edges, move straight on to the next step so it does not turn bitter.

Tip in the sliced mushrooms and spread them into a single layer. Leave them undisturbed for 3 minutes so they take on a golden colour underneath, then stir and cook for another 4 to 5 minutes. They are ready when they have shrunk noticeably, released their liquid and started to squeak against the pan.

Stir in the smoked paprika, cumin, oregano and chilli flakes, if using. Cook for 30 seconds, stirring constantly, until the spices darken slightly and smell warm and toasty rather than raw.

Add the black beans, tomato purée, vegetable stock and soy sauce. Stir well to coat everything, then simmer for 4 to 5 minutes. The sauce should thicken and cling to the mushrooms rather than pool in the pan. Taste and season with salt and pepper.

While the filling simmers, warm the tortillas. Either dry-fry them in a separate pan for 20 to 30 seconds per side, until soft and lightly blistered, or wrap the stack in foil and warm them in a 180°C oven for 5 minutes.

Spoon the filling generously down the centre of each tortilla, squeeze over fresh lime juice and scatter with chopped coriander. Serve immediately while everything is hot.