Remove core from the cabbage. Place cabbage in a large saucepan and cover with water. Bring to a boil; boil until outer leaves loosen from head. Remove cabbage; set softened leaves aside. Return cabbage to boiling water to soften more leaves. Repeat until all leaves are softened. Remove tough center stalk from each leaf. Set aside 12 large leaves for rolls. Coarsely chop enough of the remaining leaves to measure 8 cups. Place chopped cabbage in an ungreased 13-in. x 9-in. baking dish.
In a skillet over medium heat, cook pork, sausage and onion until meat is no longer pink and onion is tender; drain. Stir in rice. Place 1/2 cup meat mixture on each cabbage leaf. Fold in sides; starting at an unfolded edge, roll up leaf completely to enclose meat. Repeat with remaining meat and leaves.
Place rolls, seam side down, in the baking dish. Sprinkle with pepper. Pour broth or tomato sauce over rolls. Cover and bake at 325° for 1 to 1-1/4 hours.