Bring a large pot of salted water to a boil. Carefully remove the core from the cabbage and place the whole head in the boiling water for about 5 minutes, or until the outer leaves are tender. Remove the cabbage and let it cool slightly.

Once cool enough to handle, carefully peel off 12-14 leaves. Trim the thick vein of each leaf to make them easier to roll.

In a mixing bowl, combine the ground beef, cooked rice, chopped onion, minced garlic, paprika, salt, black pepper, and beaten egg. Mix until well combined.

Place about 2-3 tablespoons of the filling at the base of each cabbage leaf. Roll the leaf tightly, folding in the sides as you go, to secure the filling. Repeat until all filling is used.

In a saucepan, combine the tomato sauce, brown sugar, and vinegar. Simmer for 10 minutes to blend the flavors.

Preheat the oven to 350°F (175°C). Spread a thin layer of sauce on the bottom of a baking dish. Arrange the cabbage rolls seam-side down in the dish and pour the remaining sauce over the top.

Cover with foil and bake for 45 minutes. Remove the foil and bake for an additional 15 minutes, until the rolls are heated through.