Sauté them in a little olive oil until golden. Add the chopped peppers, cleaned and blanched green beans, mushrooms and stew for another 6-8 minutes. Wash and dry the zucchini and eggplants. Add them to the mixture.
Leave on the heat for 6 minutes and season with 1 tablespoon of the spices. Add the finely chopped garlic and canned tomatoes.
Cook the mixture uncovered for another 10 minutes until almost all of the liquid evaporates. Serve the ratatouille warm.