Sprinkle salt and MSG on the fish fillet. Let stand for 30 minutes.
Dip in slightly beaten egg, roll in cornstarch then fry until golden brown. Set aside.
Saute onions, celery and bell peppers in butter. Stir until half-cooked.
Season with soy sauce and MSG. Thicken with dissolved cornstarch.
Add the catsup and stir until well mixed with the sauce.
Add the fish fillet to the sauce and cook for another 3 minutes. Serve hot with rice.