Heat the oil in a frying pan and fry the onion, garlic and chilli until softened.
Add the chicken, tomatoes and kidney beans and heat through thoroughly. Stir in the coriander.
Place four of the tortilla discs onto a baking sheet brushed with oil. Top each disc with some of the chicken mixture, then sprinkle over some of the cheese.
Top with another tortilla, followed by the remaining chicken mixture and cheese.
Preheat the grill to medium or preheat the oven to 200C/400F/Gas 6.
Transfer the baking sheet to the oven or grill and cook for about five minutes, or until the tortillas are crisp and the cheese has melted, taking care not to burn the tortillas.
To serve, place a tortilla stack onto each of four plates and garnish with chopped avocado, a dollop of sour cream and some lime wedges.