Recipe from takepart.com
2 tablespoons unsalted butter or olive oil
1 large onion, chopped
1 garlic clove, smashed
Kosher salt and freshly ground black pepper
1 baking potato, peeled and diced
3 cups water
8 cups lettuce
Croutons for serving
1. Heat the butter in a medium saucepan over medium heat until hot.
2. Stir in the onion, garlic, 1 teaspoon salt, and ½ teaspoon pepper, and cook, stirring occasionally, until the onion is translucent, about 5 minutes.
3. Stir in the potato and water and simmer until the potato is tender, about 10 minutes.
4. Stir in the lettuce and cook until tender, 2 to 4 minutes.
5. Blend the soup in batches until smooth.
6. Season with salt and pepper to taste, and serve topped with the croutons.