Following the directions on the packaging, cook one cup of the Arborio rice.
In the meantime, carefully snip or slice off each leaf from the cabbage heads from the bottom of the leaf. Repeat this until you get to the leaves that are too small to use. (*See notes)
Place the leaves in a pile as you go. When done, look for leaves that might have a thicker more prominent rib travelling down the back side and trim them down (lengthwise) with a paring knife. (See photos in post above for an example.)
Dump the ground beef and pork into a large mixing bowl. Season it with the salt and pepper, then mix it thoroughly with your bare hands to make sure the seasoning is well distributed. When the rice is done, dump it directly into the meat mixture and start to mix it in with your bare hands until the rice is evenly distributed.
Preheat the oven to 350º F.
Drizzle a bit of the tomato juice into the bottom of a large baking dish or roasting pan to cover the bottom (about a cup or two).
Spoon one heaping tablespoon of the meat mixture onto the bottom center of each cabbage leaf. (*See notes.) Gently start to roll forward from the bottom up over the meat, just enough to cover it. Then, fold in the sides of the cabbage leaf and continue to roll until you’ve formed a nice and secure cabbage roll.
As you finish each cabbage roll, place them into the baking dish. When you have one whole layer covering the bottom of the pan, pour about a cup of the tomato juice over the cabbage rolls. Proceed with the rest of the cabbage rolls, placing them on top of the others as a second layer.
If you have any leftover cabbage leaves that were too small for rolling, drape them over the cabbage rolls before prior to covering them with foil and putting them into the oven. This will help keep moisture in the pan, but it’s an optional step.
Cover the pan with tinfoil and bake the cabbage rolls in the oven for 1 hour and 30 minutes.
After 1 hour and 30 minutes, remove the baking dish from the oven, remove the foil, and remove the layer of loose cabbage if you used it. If the cabbage rolls look like they need more juice, add a bit more of the tomato juice—use your best judgement. You can't really screw this up.
Cover the rolls with the tin foil again and decrease the oven temperature to 300º F. Let them back in the oven for another hour.
Remove them from the oven and check the internal temperature of a few of the rolls to ensure that the center of the meat has reached a temperature of 140-145º F.
Serve with a nice dollop of sour cream!