1. Heat the oil, and fry the zucchini, onion, garlic, and tomatoes for 30 minutes, covered.
2. Remove the cover, and cook an additional 10 to 15 minutes to evaporate any extra liquid.
3. Add the sugar, salt, and pepper; stir and remove from heat. When lukewarm, stir in the cherry tomatoes, capers, and olives. Store covered and refrigerated until ready to use.