These are all about the contrast of textures: succulent prawns and soft, ripe avocado mixed with crisp radishes and served on a lovely crunchy tortilla base. In Mexico, the tortillas are normally deep fried in oil, but I find toasting them in a dry pan works just as well and makes them much healthier. You can also make the tostadas in the oven. Brush them with a little oil, if you like, and bake them for 10–15 minutes at 180°C/Gas 4.
Put the prawns, garlic and chilli flakes into a bowl with a pinch of salt and pepper and a little drizzle of olive oil. Mix well, then set aside.
Put the avocados, spring onions, chilli, radishes and tomatoes into another bowl and mix together. Taste and season with salt, pepper and half the lime juice. Mix well, stir in the lettuce, then the coriander and set aside.
Heat a dash of oil in a heavy-based frying pan. Extract the prawns from their marinade and fry them for about 2 minutes on each side, until just cooked through. Sprinkle with the remaining lime juice and stir.
Toast the tortillas in a dry pan until nicely coloured and beginning to crisp up.
Divide the salad equally between the toasted tortillas, top with the cooked prawns and serve.
HOW TO PREPARE PRAWNS
First, twist off the head, then peel off all the shell and pull off the tail. With the tip of a sharp knife, score the prawn along the back and lift out the black vein. Rinse the prepared prawns before using.