In large skillet cook onion, celery, sweet pepper, and garlic in butter over medium heat about 5 minutes or until tender. Stir in undrained tomatoes, parsley, 1/2 tsp. salt, paprika, and ground red pepper. Bring to boiling; reduce heat. Simmer, covered, for 15 minutes.
In a small bowl stir together cold water and cornstarch. Stir cornstarch mixture and chicken into tomato mixture. Cook and stir until thickened and bubble; cook and stir for 2 minutes more or until chicken is cooked through.
Serve over rice.