Preheat the oven to 180 degrees.
Chop the onion and garlic finely.
Rinse all the vegetables and cut them into same-sized cubes.
Use a big pan and start frying the peppers, then put them to one side.
Cook the aubergines then put them to one side.
Cook the courgettes then put them to one side.
Cook the onion gently until it becomes transparent. Add the tomatoes and leave them to cook for 30 seconds more.
Mix all the grilled vegetables together gently, add the salt ad pepper, the Herbes de Provence and garlic.
Spread all the vegetables on a cooking sheet and bake them in the oven for 30-40 minutes with a sheet of aluminium foil on top.
Serve the ratatouille with salt and pepper. Pour over a drizzle of olive oil before serving.