Prepare bell peppers by cutting the tops off and removing the seeds and the ribs. Wash and set aside. In a large bowl, mix together beef, pork, onion, rice, salt, and pepper. Stuff bell peppers with meat mixture.
*If you do not have enough green peppers, then form meatballs with the remaining stuffing--this is a great way to get your kids to eat this meal, too!*
In a large pot, pour in the entire can of tomato juice. Rinse can out with 1/2 cup water. Place stuffed peppers and any meatballs into the pot. Try to submerge them as best as possible. Cover with lid and heat pot over medium-high heat. Once it comes to a boil, reduce heat to low and simmer lightly for 1-2 hours.
In a large skillet, melt shortening over medium heat. Sprinkle in flour and whisk until smooth. Cook roux until it deepens in color to be a medium brown. Stir frequently to make sure it doesn't burn.
Using a slotted spoon, remove stuffed peppers and meatballs from the pot leaving the hot cooking liquid. Pour the browned roux into remaining tomato juice (it will bubble violently for a few seconds at first, so just be aware that it is totally normal). Stir well. After a few minutes, the tomato juice should thicken and become more of a sauce. Stir in sugar and more salt and pepper. It will be sweet--as it should be :) Serve with rye bread--or any other bread you have around, but really, rye is the best.
You can use all ground beef if you don't have/can't find ground pork.