Sauerampfersuppe

(Sorrel Soup). Parboil the sorrel in 3 quarts of salted water for 2 minutes. Let stand for a few minutes more, then strain out the water and pat the sorrel dry with paper towels. Chop it very fine -- if using a food processor don't mash it too finely. Chop the parsley and vegetables, but keep these separate from the sorrel. Cook the vegetables and parsley in the broth for 40 minutes; strain them out. Reserve the broth and puree the vegetables with a little of the broth. Melt the butter in a large saucepan. Cook the minced sorrel in the melted butter for several minutes, stirring constantly. Add the clear broth and the pureed vegetables, then season with salt and pepper, lemon juice, and a pinch of sugar. Bring to a boil and cook all the ingredients together for about 10 minutes. Stir the cornstarch into the sour cream, then stir this mixture into the soup with a whisk. Bring to a boil once more. Simmer for 2 minutes. Serve with a poached or hardboiled egg in each bowl.