4 flour tortillas and a good handful mixed salad leaves, to serve
Mix half the lime juice, half the chilli, half the garlic and half the coriander with some seasoning in a shallow dish. Add the prawns and mix to coat them all. Leave to marinate while you prepare the avocado.
Roughly chop the avocado and pop it in a small food processor with the remaining lime juice, chilli, garlic, the soured cream and some seasoning. Whiz until smooth, then stir in the remaining coriander. (You could also use a stick blender for this.)
Heat the oil in a frying pan and cook the pepper for a few mins, until starting to soften. Add the prawns and fry, in a single layer, for 1-2 mins each side - you will know they are cooked when they turn pink and feel firm to the touch. Serve in warm tortillas with salad leaves, if you like, alongside the avocado cream, soured cream and some lime wedges.