Combine ground chuck, eggs, 1 small chopped onion, rice, salt, pepper, and garlic powder, mixing well. Set aside.
Turn cabbage, core side up. Using a sharp knife, make an incision across the base of the outermost leaf. Gently peel away the leaf. Repeat this process until leaves can no longer be removed without tearing.
Make additional incisions around the base of the next outermost leaves. Place cabbage, stem side up, in a colander. Pour boiling water over cabbage until leaves can be easily removed. Repeat procedure until all leaves have been removed.
Place 1 tablespoon meat mixture in the base of a cabbage leaf. Roll leaf jellyroll fashion until the mid-section is reached. Fold left side of leaf inward, and roll up remaining length of the leaf. Carefully stuff in the open end, using fingertips. Repeat with remaining meat mixture and cabbage leaves.
Sauté remaining chopped onion in shortening in a large Dutch oven. Add soup bone and tomatoes; stir gently.
Alternate layers of cabbage rolls and tomato sauce over sautéed onion and tomatoes. Do not stir. Add water to cover. Cover and cook over medium heat 30 minutes.
Add brown sugar and sour salt; stir gently. Cover and cook over medium heat 1 hour. Uncover and cook 1 hour.
Remove cabbage rolls from cooking liquid, and place on a warm serving platter. Serve immediately.