Pre-heat your BBQ over a medium heat for 2-3 minutes with the Chef Pan. Fry most of the onions and pepper in a little oil then season with salt and pepper.
Put to one side in a bowl and wipe the cooking surface with some kitchen paper.
Add a tortilla to the pan, top with cheese and a spoonful of the cooked onion and peppers. Top with another tortilla and grill on each side for 3-4 minutes until golden and the cheese has melted. Repeat for the remaining quesadillas.
Mix the remaining onion and pepper with the tomato, coriander and a drizzle of oil, then season well.
Allow the quesadillas to cool slightly before slicing, then top with the tomato relish.