Fennel bulb stewed with leeks makes a sweet-tasting soup, while the watercress finishes it with a lively, peppery flourish. Fennel is so flavorful that there’s no need to make a stock or even use the ubiquitous and trusted aromatics—bay leaf, parsley, and thyme. In fact, using water for the liquid allows the full taste of the vegetables to come forward completely unmasked.
Serve this soup with just the swirl of watercress or enrich it with a spoonful of butter. A handful of little c