In a large cast-iron or a sauté pan with a lid, heat the oil over medium heat. Add the onions and grated carrot and sauté until vegetables begin to soften.
Add the cabbage and sauté, occasionally stirring, about 5 minutes.
Meanwhile, in a medium bowl, mix ground beef with chopped onions, rice, egg, salt, black pepper, paprika, garlic powder, and nutmeg. Shape the meat mixture into meatballs and place over cabbage.
In a small bowl, mix the water, tomato paste, ketchup, sour cream, and heavy cream; season with salt and pepper to taste.
Pour the mixture over the meatballs, cover the skillet with a lid and simmer for 45 minutes over medium-low heat, turning the meatballs halfway through cooking.
Sprinkle with chopped parsley before serving, if desired.
Swap the beef with shredded turkey or chicken for a leaner option.
Substitute the rice with quinoa for lower carbs.
Shape the meatballs as large or small as you like.
Cast iron is oven-safe (make sure the lid is too), so you can move it from the stovetop directly into the oven. It will cook everything evenly and eliminate turning the meatballs half-way through the cooking.