Potato Soup - cooking recipe

Ingredients

3 large potatoes, sliced 1/4-inch thick
1 small onion, chopped or sliced
1/2 tsp. salt
4 c. water
1 or 2 Tbsp. parsley

Preparation

Boil the above ingredients until potatoes are tender.
Make a roux with 2 tablespoons butter and 1 tablespoon flour; add some liquid from soup.
Combine the mixtures and cook about 5 minutes. Add vinegar to taste, a little less than 1/4 cup.