Many of Sarah’s foreign recipes were as complicated as something out of Mastering the Art of French Cooking—but this one is easy, and delicious.
Put the water into a 3- to 4-quart pot, and then add the potatoes and mushrooms. Bring to a boil; then lower the heat to a simmer.
Meanwhile, fry the bacon until it’s crisp. When it’s done, pour off most of the fat; add the flour to the pan, and stir until combined.
Add the bacon and flour mixture to the pot with the potatoes and mushrooms. Simmer until the potatoes and mushrooms are soft. Add the sour cream and stir to combine.
Season to taste with pepper, and serve with a hearty bread. (Sarah likes to serve this soup with pumpernickel rolls.)