Cut shrimp in half. Cook onion and green pepper in margarine until tender. Drain pineapple and reserve juice. Combine juice with vinegar, sugar, cornstarch, soy sauce, dry mustard. Shake together until well blended. Add to cooked vegetables. Cook, stirring constantly, until thick and clear. Gently stir in pineapple chunks, cherry tomatoes, and shrimp and heat thoroughly. Combine cooked rice and almonds. Serve shrimp mixture over rice mixture.