A popular dish from the French region of Provence that combines eggplant, tomatoes, onions, bell peppers, zucchini, garlic and herbs — all simmered in olive oil. The vegetables can vary according to the cook. They can be cooked together, or cooked separately and then combined and heated briefly together. Ratatouille can be served hot, cold or at room temperature, either as a side dish or as an appetizer with bread or crackers.