Good Tuna And Potato Casserole - cooking recipe

Ingredients

4 c. thinly sliced pared potatoes
3 Tbsp. butter or margarine
1/4 c. flour
2 Tbsp. prepared mustard
2 c. milk
1 tsp. salt
1/8 tsp. pepper
1 (7 oz.) can tuna, flaked (1 c.)
1 c. thinly sliced, peeled onions

Preparation

Cook potatoes in boiling salted water for 10 minutes.
Drain. Melt butter in top of double boiler over direct heat.
Stir in flour, then mustard.
Add milk, salt and pepper and stir over boiling water until smooth and thickened.
Arrange potatoes, tuna and onions in alternate layers in greased 2-quart casserole.