Heat a large pot with oil, preferably olive oil, over medium heat.
When the oil is hot, add the onion and pepper. Stir well.
When the onion begins to become translucent, add the garlic in large pieces. Stir well to allow everything to brown.
When the onions and peppers are browned, add the eggplant, zucchini, and sprinkle with a pinch of salt. Stir well and let cook until the vegetables release some of their water.
When the vegetables have softened, add the rest of the ingredients: the tomato, water, broth, herbs, pepper, and olives if desired.
Lower the heat, cover, and let simmer for about 30 minutes, stirring occasionally. Add water if it seems too dry.
When cooked, the vegetables should look well confit. Remove from heat and serve as a side with pasta, rice, a protein, or on their own for a light meal.