Preheat the oven to 350 degrees.
Cook the cabbage in boiling water until outer leaves pull away from head. Remove 12 large leaves from the head and set them aside for rolls. Finely chop the remaining cabbage and place it in the bottom of a 9x13 baking dish.
Combine the beef, pork, 1/2 cup tomato sauce, onion, rice, and salt in a large bowl. Mix well.
Cut out the thick vein from the cabbage leaf, making a V-shaped cut at the bottom of each leaf. Place around 1/4 cup of the meat mixture on a cabbage leaf.
Overlap the cut ends of the leaf and fold in the sides. Beginning from the cut end, roll up the cabbage leaf and place it on top of the chopped cabbage in the baking dish, seam side down. Repeat with remaining leaves.
Combine the tomatoes, sugar, Italian seasoning, and remaining tomato sauce in a small bowl. Stir to mix.
Pour the sauce over the rolls.
Cover and bake until the cabbage rolls are tender, around 1 1/2 hours.