Here sorrel brings both acidity and lightness to an often heavy mixture. You can substitute watercress or spinach for the sorrel to similar effect, especially if you add a squeeze of lemon at the end. Though it has only two primary ingredients, this soup is quite complex, particularly when you begin with good stock. The best lentils to use here are lentilles du Puy or other small dark green ones. Use the greenish brown variety only if you cannot find these.
Recipe information
Yield
makes 4 servings
Ingredients
Preparation
Step 1
Place the lentils in a large saucepan and add the stock. Simmer over low heat until softened, 30 minutes or so.
Step 2
Meanwhile, melt 1 tablespoon of the butter in a deep skillet over medium heat and cook the sorrel until softened, about 5 minutes. Stir the sorrel into the simmering lentils along with the salt, pepper, and sugar; bring the mixture to a boil, then lower the heat and simmer, stirring occasionally, for about 10 minutes.
Step 3
At this point you can adjust the seasoning—now is the time to add lemon if you think the soup needs some—and serve, or you can puree the soup, which is somewhat more elegant. To do so, use a food mill, an immersion blender, or an upright blender and puree the mixture until smooth, working in batches if necessary. (In this as in every instance, take care when pureeing hot liquid; it’s best, if you have the time, to let the mixture cool to room temperature before pureeing.) Reheat the soup in the pan and stir in the remaining butter, or cover and refrigerate the soup for up to a couple of days, adding the butter (and a little water if necessary) when you reheat it.
