3 T Butter 3 C sliced or minced leeks 3 T flour 6 C very hot water 2 tsp. salt 4 C diced potatoes (use the red waxy potatoes, so they keep their shape)
Melt butter in saucepan over medium heat. Add leeks and cover. Cook for 5 minutes; do not brown. Add flour and cook for 2 minutes; do not brown. Add 1 cup of very hot water and break up the roux. Add remaing water, salt and pepper to taste. Simmer for 40 minutes.
Just before serving, add milk and 1 T butter. Offer sour cream as garnish at table.