2 cups warm cooked rice (*substitute cauliflower rice if you’re so inclined)
2 carrots, shredded (1/2 cup)
1 head green cabbage
1 (14oz) can tomato sauce
Warm 2 tbsp. of the butter over medium heat, then add the onion and sauté until softened, about 6 minutes. Add the garlic and sauté for another minute, then add the ground beef, 1 tsp. of the pepper, salt, dill, and mustard powder. Continue to cook, stirring frequently, until most of the pink has been cooked out of the beef, about 6 minutes. Stir in the cooked rice and carrots, then remove from the heat and set aside as you prepare the cabbage.
Cut out the core of the cabbage. Bring a stockpot of water to a boil on high heat. Drop the cabbage into the boiling water and press it down with a wooden spoon, boiling for 5 minutes. Carefully remove the cabbage from the water using 2 forks and strain in a colander for 1 minute, but keep the water boiling. Peel off the softened cabbage leaves, stopping when the leaves get hard and dry. Return the head of cabbage to the water, repeating the process.
Heat the remaining 4 tbsp. butter in a saucepan on low. Stir in the tomato sauce and the remaining 1/2 tsp. pepper; allow to simmer while you make the rolls. Place the softened cabbage leaves on a cutting board and shave off the excess spine from the outer side of each leaf. Spoon some filling into the base end of the cabbage leaf and roll it together, tucking in the sides as you roll. One head of cabbage should yield 15-18 rolls.
Preheat the oven to 325° F. Place the rolls in a casserole dish, then spoon the tomato sauce over the rolls. Bake until cooked through, about 40 minutes.