In a large bowl, combine the pork, onion, rice, egg, salt and ground black pepper. Mix well and form into 2 inch balls.
For stove: Place one jar of the sauerkraut in a large pot over medium low heat. Then add the pork balls and cover with the other jar of sauerkraut. Simmer over medium low heat for 1 to 1 1/2 hours.
For slow cooker: Place one jar of sauerkraut in the bottom of the slow cooker. Add the pork balls and top with the other jar of sauerkraut. Cook on low setting for 8 to 10 hours.
