Coat the bottom of a Dutch oven or soup pot with olive oil and saute the onions with a little salt and pepper over medium heat until translucent. Do not let them brown. Add the minced garlic and saute until aromatic. Add the cubed eggplant and continue to saute. Add more olive oil if needed. Turn the heat a bit higher and brown the eggplant lightly. If the mixture is too dry, add water.Reduce the heat to medium. After 5 - 7 minutes, add the red and green bell peppers, then the herbs. After another 5 to 7 minutes, add the zucchini. Add the tomatoes last. Simmer until the vegetables are tender, stirring occasionally. Add water if necessary. Taste and add salt and pepper if needed. Total cooking time should be about 30 minutes.