Trim the thick vein from each cabbage leaf by cutting a small V shape from the center of the stem end.
Incorporate the cooked rice, diced tomatoes, and 1/4 cup of tomato sauce into the meat mixture, followed by the egg. Remove from heat.
Pour the rest of the sauce evenly over the cabbage rolls. Cover the dish tightly with foil. Bake in a 350°F oven for 75 minutes. Remove the foil and bake for an extra 10 minutes.