Pasta with Zucchini and Tomatoes

1 onion
1 clove garlic
2 zucchini, about 1/2 lb. total
1 T. oil
14 1/2 oz. can tomatoes
1/2 tsp. dried oregano
Salt and pepper
1 T. chopped fresh parsley
1/2 lb. spaghetti
1 T. drained capers (optional)

Chop onion. Mince garlic. Cut zucchini lengthwise into quarters and then into slices. Put oil, onion and garlic in a one quart microwave safe dish. Cover and cook on High 3 minutes, stirring once. Stir in zucchini. Cover and cook on High 2 minutes. Add tomatoes and their juice, the oregano, 1/2 tsp. salt, 1/2 tsp. pepper and the parsley. Break up tomatoes with a spoon. Cover and cook on High until thickened, stirring every 5 minutes, 10 to 15 minutes. Meanwhile, cook spaghetti in a large pot of boiling water until done; drain. Stir capers into sauce and serve over spaghetti.