Place prunes and lemon in a saucepan, cover with cold water, and bring to a boil. Reduce heat and simmer uncovered for 30 minutes. Drain, discard the lemon, and chop the prunes. Place them in a large mixing bowl and set aside. In a heavy skillet, brown the sausage. Transfer the sausage to the bowl with the prunes. In the remaining pan drippings, saute the onions and apples for 5 minutes over medium heat. Stir in the stock and herbs, and simmer over low heat until the onions and apples are soft. Add the bread crumbs and stir gently. Transfer to bowl with prunes and sausage. Toss until well blended. Season with salt and pepper.