Bring a large pot of water to a boil, then remove the stem from the cabbage and submerge the whole head. Let it cook for 3 to 5 minutes until the leaves soften enough to peel off.
Carefully separate 8 cabbage leaves from the head, trimming the thick vein by cutting a 'V' shape to help them roll easily. Set aside.
Combine the crushed tomatoes, brown sugar, and red wine vinegar in a saucepan and simmer gently for 15 minutes, then set the sauce aside.
Heat your oven to 350 degrees Fahrenheit.
Melt butter in a skillet over medium heat; add diced onion and cook until translucent, about 5 minutes. Stir in minced garlic and cook for an additional minute. Transfer this mixture into a mixing bowl.
Add ground beef, cooked rice, egg, chopped parsley, salt, and pepper to the bowl with onion and garlic. Mix thoroughly until everything is evenly combined.
Shape the meat mixture into small logs roughly 4 inches in length and 2 inches wide.
Place each meat log onto the center of a cabbage leaf, then roll it up tightly while folding in the sides. Repeat for all leaves and filling.
Pour half of the prepared tomato sauce into the bottom of a 9x13 baking dish, arrange the cabbage rolls in a single layer, then pour the remaining sauce over the top.
Bake in the preheated oven for 1 hour. Allow the rolls to rest for about 10 minutes before serving.
