Preheat the oven to 180°C/gas mark 4. Cut the wraps into triangles and brush each one all over with the oil. Season well, then put on a baking sheet in the oven for 10-12 minutes, until golden brown and crunchy.
Peel the avocado and mash in a bowl with the red onion, garlic and lime juice. Combine the tomatoes, onion, white wine vinegar and coriander to make the salsa.
Grate the cheese. To serve, pile half the nacho chips into a serving platter and top with half the guacamole, salsa, chicken and cheese. Scatter over the remaining chips, then repeat with the rest of the toppings. Place them under a preheated grill for a few minutes if you prefer the cheese melted.