Custard Mystery - cooking recipe

Ingredients

1 c. sugar
2 Tbsp. flour
2 Tbsp. shortening
2 egg yolks
2 egg whites
1 lemon (juice and a little rind)

Preparation

Beat to a cream and add beaten egg whites last to which has been added 1/4 teaspoon salt.
Put in baking dish and set in a dish of hot water.
Bake in moderate oven 30 minutes.