Heat 2 tablespoons of the oil in a large frying pan and stir-fry the sliced turkey for 3–4 minutes until it is beginning to colour, then remove it with a slotted spoon. Increase the heat, add the remaining oil and fry the onion and peppers for 5–6 minutes, stirring only occasionally so that they colour quickly without softening too much.
Reduce the heat, return the turkey to the pan and stir in the beans and cooked rice. Season well, squeeze over the lime juice and remove from the heat. Spoon the filling on to the tortillas, roll them up and arrange them in a rectangular ovenproof dish.
Pour the salsa over the tortillas and scatter over the jalapeño peppers (if used) and Cheddar. Cook in a preheated oven, 200°C (400°F), Gas Mark 6, for about 20 minutes, until hot and the cheese has melted. Serve immediately with guacamole and shredded lettuce.