Recipe(tried): Patio Potato Salad (Potato Salad with Cooked Dressing)

Barbara, Here's a recipe I've had for over 25 years. Hope it's what you're looking for.

PATIO POTATO SALAD

FOR THE DRESSING:
1/2 cup milk
1/4 cup vinegar
1 egg
1/3 cup flour
4 Tbsp margarine
1 tbsp cornstarch
1 tsp celery seed
1/4 tsp dry mustard
FOR THE SALAD:
7 medium potatoes, peeled, cooked, and sliced or cubed
1/4 cup chopped onion
1/4 cup mayonnaise

Mix dressing ingredients together in a saucepan and cook until thick, stirring frequently. Remove from heat and cool.

Combine the salad ingredients in a bowl. Add the dressing and stir to combine. Chill.