From America's Test Kitchen Season 3: Hearty Soups
Rustic potato-leek soup often disappoints with soft, mealy potatoes and dingy, overcooked leeks. We wanted to perfect this soup so both ingredients would be at their best and the dish would retain its textural integrity and bright flavor. We quickly eliminated potatoes with high or medium starch levels because they broke down too quickly in the chicken broth. Waxy, low-starch red potatoes were perfect—they kept their shape and didn’t become waterlogged during cooking. To pump up the flavor of the soup, we used a substantial amount of leeks and sautéed both the white and light green parts in butter. Leeks and potatoes require different cooking times, so we staggered the cooking—leeks first, then potatoes, and then we removed the pot from the stove so the potatoes could gently cook through in the hot broth without becoming overcooked and mushy. We also added a bit of flour with the sautéed leeks to give our broth some body. At long last, we had a flavorful, oniony soup, full of perfectly cooked potatoes and sweet, tender leeks.
Makes about 11 cups, serving 6 to 8
Leeks differ. If yours have large desirable white and light green sections, use 4 pounds of leeks; if they’re short on these parts, go with 5 pounds.