Make the salsa. Rub 1 tablespoon of the oil over the red pepper, then cook under a preheated hot grill for 10–12 minutes, turning frequently, until charred. Place in a bowl and cover. When cool enough to handle, peel away the skin, remove the seeds and membrane, then finely chop the flesh. Mix together with the remaining oil, the lime juice, a little lime rind and the coriander. Season. Set aside.
Rub half the oil over the corn cobs. Cook in a hot griddle pan for 3 minutes on each side, then remove from the pan. Using a sharp knife, slice the sweetcorn kernels away from the cobs. Meanwhile, use tongs to hold a tortilla over a gas flame until softened and lightly charred. Repeat with the remaining tortillas.
Mix together the soured cream with the remaining lime rind from the salsa and the chilli powder. Pile the sweetcorn and prawns on to the tortillas. Scatter over the spring onion and lettuce, then top with some red pepper salsa and the chilli soured cream. Serve immediately.