potatoes, cooked and diced
onions to taste
salt to taste
celery seed to taste

Mayonnaise:

3 level tbsp. sugar
1 tbsp. flour (rounded)
1 tsp. dry mustard
1 tsp. salt
1/2 tsp. pepper
2 eggs
1/2 c. vinegar plus 1 c. water
2 to 2 1/2 tbsp. butter

Mix first 5 ingredients together. Add remaining ingredients. Boil, stirring constantly, until thickened. Cool and pour over potato mixture.