Preheat the oven to 325 degrees F (165 degrees C). Grease a 2-quart casserole dish.

Fill a large pot with a few inches of water and insert a steamer basket; bring to a boil. Place whole head of cabbage into the steamer basket, cover, and steam until tender, 10 to 12 minutes.

Bring 3 cups water to a boil in a saucepan. Stir in rice and reduce the heat. Cover and simmer until rice is tender and water has been absorbed, about 20 minutes.

Melt butter in a small skillet over medium heat. Add onion and sauté until translucent, about 5 minutes. Stir onion into cooked rice and season with salt and pepper to taste.

Cut leaves off cabbage and cut any larger leaves in half. Spoon 1 tablespoon rice into each leaf and roll tightly.

Stack rolls in layers in the prepared casserole dish. Pour tomato juice over the rolls, using enough just to cover.