Melt half of the butter in a large skillet. Add the onions, stir, and then let them simmer for 10 to 15 minutes over medium heat, or until reduced in size caramelized in color.
In a large mixing bowl, add the caramelized onions (leaving the butter behind in the pan), the blended livers, the beef, the drained sauerkraut, the salt, and the pepper. I suggest using your hands to incorporate the ingredients into an even mixture.
Add the rest of the butter to the original skillet and turn the heat to medium. Form the mixture into meatballs and place them in the pan. Cook the meatballs on each side for 3 to 4 minutes, or until slightly charred.
Stove top variation: Continue to rotate each meatball 3 to 4 times so that you have a nice char on all sides. Add more butter/olive oil to the pan, if needed.
Oven variation: After charring on one side, flip the meatballs over once and transfer to the oven. Cook at 350 for 20 minutes, or until cooked through.
Stove top variation: Continue to rotate each meatball 3 to 4 times so that you have a nice char on all sides. Add more butter/olive oil to the pan, if needed.
Oven variation: After charring on one side, flip the meatballs over once and transfer to the oven. Cook at 350 for 20 minutes, or until cooked through.
Garnish with additional salt (as you like) and serve warm!