1. In 6-quart Dutch oven or saucepot over medium heat, cook onion and garlic in hot olive oil until tender, about 10 minutes, stirring occasionally.
  2. Add eggplant and the green pepper; cook for 5 minutes, stirring frequently.
  3. Stir in zucchini, water, salt, oregano and sugar; heat to boiling.  Reduce heat to medium-low and cook 10 minutes.
  4. Stir in tomatoes and cook for an additional 20 minutes or until vegetables are tender, stirring occasionally.  Serve hot or follow step 5.
  5. Cover vegetable mixture and refrigerate to serve cold later.