Set the oven to 160 ° C (convection). Heat oil in a pot. Fry the onions and garlic in it over medium heat. Add tomatoes, peppers, vinegar, sugar and chilli and cook for 6-7 minutes until the liquid has evaporated. Add corn and heat for 3 minutes.
Layer the tortilla chips, sauce and cheese in a baking dish; the last layer should be cheese.
Brush with sour cream and bake uncovered in the oven for 15 minutes.
It also looks nice if you decorate the casserole with fresh, chopped chives shortly beforehand.