Preheat the oven to 350°F (for a faster bake) or 200°F (for a slower simmer).

Use a sharp knife to cut out the central hard core of the cabbage. In a large pot, bring 6 quarts water to a boil over high heat. Carefully drop the biggest outer leaves of the cabbage into the boiling water. Boil until the leaves are soft. After 2 minutes, remove the leaves to a large platter to cool.

Shred the remainder of the cabbage and set aside.

Sauté the minced onion until tender. In a large bowl, combine the sautéed onion, beef, rice, egg, ½ cup of the chicken stock, and pepper. Set aside.

In a second large bowl, toss the shredded cabbage, sliced onion, and sauerkraut.

In a third large bowl, whisk the tomato paste and the crushed tomatoes with the remaining 2 cups stock.

On the bottom of a 6-quart casserole dish or Dutch oven, spread half of the sauerkraut mixture to make a bed for the cabbage rolls. Evenly spoon half of the tomato mixture over the sauerkraut mixture.

To stuff the cabbage, place a cabbage leaf in front of you with the stem end facing down and away from you. Place a scoop of the meat and rice mixture in the middle of the leaf. Fold the bottom (stem end) of the leaf down toward the top of the leaf, then fold the right side inward and over toward the left. Fold down the top of the leaf and push the left edge inside to create a pocket. You want the package to have some space in it for the rice to swell as it cooks. Place the roll seam side down into the prepared casserole dish or Dutch oven. Repeat until you have stuffed all the cabbage leaves and filled the dish with one layer of stuffed cabbage. Spread the remaining sauerkraut mixture and the remaining tomato mixture on top.

Bake until the sauce is bubbling, about 30 minutes. Cover the baking dish with foil or place the lid on the Dutch oven and continue cooking for 5 hours at 350°F or 8 hours at 200°F.