For the salsa, mix all of the salsa ingredients together in a bowl and season to taste with salt and freshly ground black pepper.
Tip the avocado into a mixing bowl with the lime juice to prevent it from turning brown. Add the garlic, crème fraîche and coriander and mash everything together lightly with a fork, keeping plenty of texture. Season to taste with salt and freshly ground black pepper.
For the quesadillas, lay two of the tortillas out on a flat surface. Top each with the cheese, followed by the chicken, peppers and coriander. Place the remaining tortillas on top and press down gently.
Heat a frying pan over a medium hot and add one of the quesadillas to the pan. Fry, without adding any oil, for 2-3 minutes on each side or until the tortilla is crisp, the cheese melted and the chicken heated through thoroughly. Keep warm whilst you cook the second quesadillas.
To serve, cut the quesadillas into quarters arrange on plates. Spoon a little soured cream on top, garnish with coriander and serve with the salsa and guacamole on the side.