Place cabbages in a large stockpot filled halfway with water; add vinegar. Cover and steam over low heat until leaves are tender, 1 to 1 1/2 hours. Remove cabbages, reserving vinegar cooking water. Rinse with cold water to chill the cabbage, then separate the leaves.

Meanwhile, bring 3 cups water and rice to a boil in a saucepan over high heat, then reduce heat to low, cover, and simmer until the rice is tender, about 20 minutes. Remove from heat and fluff with a fork; set aside to cool.

Heat a large skillet over medium heat. Brown the ground beef and sausage with the onion, salt, garlic salt, and pepper, 7 to 10 minutes. Drain and set aside to cool.

Preheat oven to 325 degrees F (165 degrees C). Cover the bottom of a large roasting pan with a single layer of cabbage leaves.

Prepare the filling by stirring together the rice, cooked meat, and sauerkraut until well blended. Place 1/3 cup of filling into each leaf and roll into a cylinder, tucking in the ends as you roll it up. Place the rolls into the roasting pan. Pour in enough of the cooking liquid from the cabbage to come halfway up the sides of the rolls. Cover pan with a tight fitting lid or aluminum foil.

Bake in preheated oven for 1 1/2 hours. Serve warm or at room temperature.