Rince and cut all vegetables into cubes or strips.
Mince garlic and onion.
1 traditionnal method
Heat olive oil in 3 different pans or in a skillet one time after the other. Fry in each 1/3rd of onion and garlic with one of the 3 vegetable: zucchini, then eggplant, then red bell pepper. Season with salt, pepper and herbes de Provence.
When vegetables are soft, pour into a large pan.
2 quick method
Pour olive oil in a large pan. Fry onion and garlic for a few minutes.
Then add bell pepper, fry for 5-10 more minutes, stirring occasionally.
Season with herbes de Provence, salt and pepper.
Then add zucchini, fry again for 5-10 minutes, stirring occasionally. Add more olive oil if necessary.
Finally add eggplant and fry again. Same thing adding olive oil if necessary and stirring occasionally.
Then let it cook slowly
Finally add cubed tomatoes or tomato pulp and bay leaves.
Cook for 20 min to 1 hour at medium-low heat. Adjust seasoning if necessary.