Hot Potato Salad - cooking recipe

Ingredients

1 egg
1/2 tsp. dry mustard
1/2 c. white vinegar *
1/2 c. water
2 Tbsp. cornstarch
2 Tbsp. water
1 c. sugar
1 chunk butter or oleo
8 medium potatoes, cooked and diced
1 small onion, chopped
hard-boiled eggs (optional)

Preparation

*Note:
Do not use Heinz or cider vinegar.