Ingredients
1 large onion, coarsely chopped
1 garlic bulb (about 16 cloves), cloves lightly crushed with the flat side of a large knife
1 medium russet potato (about 1/2 pound), peeled and cubed
Scant 1/2 teaspoon saffron threads
1 bay leaf
Pinch of crushed red-pepper flakes
1 teaspoon coarse salt
2 ounces fresh sorrel leaves, cut into 1/2-inch strips
4 1/2 teaspoons fresh lemon juice (or to taste)
8 thin slices baguette
1 teaspoon extra-virgin olive oil
Freshly ground pepper
Preparation
Combine 7 cups water, the onion, garlic, potato, saffron, bay leaf, red-pepper flakes, and salt. Bring to a boil in a medium saucepan. Reduce heat to medium; simmer, partially covered, 30 minutes.
Pour soup through a fine sieve into a bowl, pressing on solids with a ladle to extract all the liquid and force through 1/2 cup solids. Return liquid and puree to pan; bring to a simmer over medium-high heat. Stir in sorrel; cook until wilted, about 3 minutes. Stir in lemon juice.
Preheat oven to 375 degrees. Arrange bread slices on a rimmed baking sheet. Using 1 teaspoon oil, lightly brush one side of each slice. Season with pepper. Bake until golden brown, about 8 minutes.
Divide soup among 4 bowls. Drizzle each serving with 1/2 teaspoon oil. Serve soup with baguette croutons.
