Bring a large pot of water to a boil while you prep your cabbage. Using a pairing knife carefully remove the bottom core, while leaving the head in tact, and remove any damaged outer leaves, then set aside. When water is boiling, add both heads and press down with a wooden spoon. If the cabbage will not stay submerged, weigh down with a your wooden spoon or a heat-safe pot lid.

Boil heads until the outer layers of leaves soften, about 5 minutes. You'll know the leaves are ready when they are bright green and easily pull away from the center. Remove heads with two spoons and place in a colander. Using the two spoons, peel off softened outer layers of leaves, then return to the boiling water. Repeat this process until 3/4 of the head is softened and removed. Alternatively, you can peel all leaves before par-boiling, however I find the leaves tear easier. Handle with caution.

Layer cooked leaves on a paper towel lined platter to dry and cool.

In a large high-sided skillet, heat butter or ghee over medium heat, and cook onions and carrots until slightly softened, about 5 minutes. Add garlic and cook another 1 minute, stirring constantly.

Add ground meat, salt, pepper, mustard and dill, and mix with onion and carrot mixture. Brown meat throughout, breaking up pieces as they cook. Remove from heat and stir in cooked rice, mixing until well combined. Let cool slightly.

While your meat is cooking, and when the cabbage leaves are cool enough to handle, flip individual leaves upside down on a cutting board. Using a small pairing knife, scrape off any tough portions of the spine at the base of the leaves. Flip leaves back over in preparation for filling.

Preheat oven to 325, and prepare a large baking dish by spreading a few tablespoons of tomato sauce in the bottom.

When the meat mixture is cool enough to handle, use a large spoon to scoop mixture into the bottom 1/3 of the cabbage leaf, near the base. Use 1 large spoonful for smaller leaves and 2 for larger leaves.

Using your pointer and middle fingers to stabilize the leaf, then fold in the sides using your thumbs. Roll the leaf upwards, tucking in the sides as you go, much like a cigar or sushi roll. Place roll in the prepared baking dish, and continue until all meat mixture is used. Nestle the rolls together but don't overcrowd them, you should have 16-20 total. Bake in preheated oven for 35-45 minutes, until heated through and sauce is bubbling. Remove from oven and let rest a few minutes before serving.