Sorrel-Lentil Soup

It’s difficult to imagine how a recipe as simple as this one can also be so good. This recipe is derived from one of Elizabeth David’s, which calls for only lentils, sorrel, and cream. I have never been able to resist adding some red onion and bay leaf, and sometimes a mirepoix of celery and carrots. But even with these additions this is the simplest of soups. There is no browning of onions or sautéin