- 2 tablespoons unsalted butter
- 1 small onion, coarsely chopped (about 1 cup)
- 1 small head cauliflower (about 1 3/4 pounds), cut into 1-inch florets
- 2 cups homemade or low-sodium store-bought chicken stock
- 2 1/2 teaspoons coarse salt
- Freshly ground pepper
- 1 bunch watercress, thick stems removed (about 5 cups), plus small sprigs for garnish
Melt butter in a medium saucepan over medium heat. Add onion; cook, stirring occasionally, until soft and translucent, about 5 minutes. Add cauliflower, stock, salt, 1/4 teaspoon pepper, and 2 cups water. Bring to a boil. Cover, and reduce heat. Simmer, stirring once, until cauliflower is very tender, about 15 minutes. Remove from heat, and stir in watercress.
Working in batches, puree soup in a blender, filling no more than halfway each time. Return soup to saucepan; cover to keep warm. To serve, divide among 4 bowls. Garnish each bowl with a sprig of watercress, and season with pepper.