Preheat your oven to 350°F.
In a large pot of boiling salted water, cook the whole cabbage head for about 15 to 20 minutes until the leaves are tender.
Carefully remove the cabbage and let it cool slightly.
In a mixing bowl, combine the ground beef, cooked rice, chopped onion, minced garlic, egg, salt, and pepper.
Mix everything well until it is combined thoroughly.
Separate the cabbage leaves carefully.
Cut a V-shaped notch to remove the thick vein from each leaf.
Place about 1/4 cup of the meat mixture on a cabbage leaf, then roll it up tightly.
Place the cabbage rolls seam side down in a baking dish.
In a separate bowl, mix together the tomato sauce and water and pour it evenly over the rolls.
Cover the baking dish with aluminum foil and bake for about 1 hour until the rolls are thoroughly cooked.
Remove the foil during the last 15 minutes of baking to let the tops brown a bit.