Trim excess fat from lamb shoulder; cut lamb into 1-inch cubes. Cook and stir lamb, onion and garlic in oil in 4-quart Dutch oven until lamb is no longer pink; drain. Stir in broth, salt, juniper berries and pepper. Heat to boiling; reduce heat. Cover and simmer, stirring occasionally, until lamb is tender, about 1 hour. Shake flour and water in a tightly covered container; stir into lamb mixture. Boil and stir 1 minute. Stir in chiles. Sprinkle each serving with lemon peel.
