Active Time

　　25 min

　　Total Time

　　35 min

　　This soup is a great way to use lettuce's outer leaves and ribs, which usually go to waste. Any kind of potato and any salad greens, including lettuce, arugula, spinach, and watercress, will work fine.

　　

Ingredients

Makes 4 servings

　　1 cup chopped onions, scallions, and/or shallots

　　1 garlic clove, chopped

　　3 tablespoons unsalted butter

　　3/4 teaspoon ground coriander

　　3/4 teaspoon salt

　　1/4 teaspoon black pepper

　　3/4 cup diced (1/3 inch) peeled potato

　　8 cups coarsely chopped lettuce leaves including ribs (3/4 lb)

　　3 cups water

　　

Step 1

Cook onion mixture and garlic in 2 tablespoons butter in a 4- to 5-quart heavy pot over moderately low heat, stirring, until softened, 3 to 5 minutes. Add coriander, salt, and pepper and cook, stirring, 1 minute. Stir in potato, lettuce, and water and bring to a boil, then reduce heat and simmer, covered, until potato is very tender, about 10 minutes.

　　

Step 2

Purée soup in batches in a blender (use caution when blending hot liquids) and transfer to a 2- to 3-quart saucepan. Bring soup to a simmer, then whisk in remaining tablespoon butter and salt and pepper to taste.