Because sorrel is so delicate, it needs only a brief simmering to release its enticing flavor.
1 pound sorrel
3 tablespoons butter
2 medium onions, coarsely chopped
1/4 teaspoon cayenne
6 cups chicken broth
2 mealy potatoes, peeled and cubed
1 bay leaf
1 teaspoon dried chervil
1 cup medium or whipping cream
1/2 teaspoon salt
1. Rinse the sorrel and remove the tough stems. Stack the leaves and cut across into thin shreds. Set aside.
2. Melt the butter in a large saucepan. Add the onions and toss to coat evenly. Sprinkle on the cayenne and stir over medium heat until the onions are tender. Pour in the chicken broth. Add the potatoes, bay leaf, and chervil. Cover the pan and cook at a gentle bubble until the potatoes are tender.
3. Transfer to the container of a blender or processor and whirl until smooth. Return to the saucepan and blend in the cream. Stir in the sorrel and salt and place over low heat. Simmer gently for 5 minutes or until the sorrel is wilted. Ladle into soup bowls and serve hot, or cover and refrigerate until chilled and serve cold.