Heat 2 tbsp olive oil in a large pan over medium heat. Sauté the eggplant for 5–6 minutes until slightly softened. Remove and set aside.
Add 1 tbsp olive oil, cook zucchini for 3–4 minutes. Remove and set aside.
Add the remaining olive oil, sauté bell peppers for 4–5 minutes. Remove and set aside.
In the same pan, cook onion for 3 minutes, then add garlic and cook for 1 minute.
Add chopped tomatoes and herbs de Provence. Simmer for 5 minutes.
Return all vegetables to the pan. Season with salt and pepper. Stir gently.
Cover and simmer on low heat for 15–20 minutes until vegetables are tender.
Garnish with fresh basil and serve warm.