1/3 c. chopped onion
1/3 c. chopped celery
2 tbsp. butter
1 (8 oz.) can tomato sauce
1/4 c. prepared mustard
2 tbsp. brown sugar
1 1/2 lbs. fish fillets

Saute onion and celery in butter until lightly browned. Add tomato sauce, mustard, and brown sugar. Simmer, uncovered, for 10 minutes. In shallow, ungreased baking dish, spoon sauce over fish.

Bake uncovered at 350 degrees for about 25-30 minutes until fish flakes easily.