Potato Salad - cooking recipe

Ingredients

8 large cold boiled potatoes, sliced thin
1 yolk hard-boiled egg, mashed fine
1 tsp. minced mustard
4 Tbsp. melted butter
4 Tbsp. vinegar
dash of pepper
1 onion, finely chopped

Preparation

Mix all ingredients, except potatoes, together until blended well.
Add potatoes; mix together.
Garnish with bits of beet and white of egg, lettuce, parsley or cress.