Lentil Soup with Sorrel

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.