In skillet, cook onion, celery and garlic in shortening until tender but not brown. Add tomatoes, tomato sauce and next 5 ingredients. Simmer uncovered for 45 minutes. (I use cover to keep from spilling.)
Mix cornstarch with 1 tablespoon cold water; stir into sauce. Cook and stir until mixture thickens and bubbles. Add shrimp and green peppers. Cover: simmer 5 minutes. Serve over rice. Serves about 6.