Cut the cabbage in half lengthwise and remove the core. Peel a couple of the outer leaves away from the cabbage halves and discard. Bring a pot of salted water to a boil. Add the cabbage and cook for 20 minutes or until tender. Remove from the water and cool completely. Carefully divide into individual leaves (eight whole leaves are needed). Set aside. In a large saute pan, over medium heat, melt the butter. Add the meat. Season with salt and pepper. Brown the meat for 5 minutes. Add the onions. Season with salt and pepper. Continue to cook for 4 minutes, or until the onions are translucent. Remove from the heat and turn into a mixing bowl. Cool slightly. Stir in the rice, egg and parsley. Mix well. Season with salt and pepper. Preheat the oven to 375 degrees F. Place 1/2 cup of the meat and rice mixture in the center of each cabbage leaf. Roll up each leaf tightly. Place in a shallow baking pan, add the water and cover with foil. Bake for 30 minutes. In a saucepan, over medium heat, melt the butter. Stir in the flour and cook for 4 minutes for a blonde roux. Stir in the tomatoes, garlic and sugar. Season with salt and pepper. Continue to cook for 2 minutes. Stir in the stock and the thyme. Bring the liquid to a boil, reduce to a simmer and continue to cook for 15 minutes or until the sauce coats the back of a spoon. To serve, spoon the sauce in the center of each plate. Arrange two of the stuffed cabbage leaves in the center of the sauce.