Season the hamburger well with salt and pepper and add the egg. Mix well. Mix in rice. To make sauce, melt the butter and add the tomato soup and an equal amount of water and add to onion. Add the parsley, celery, lemon juice, sugar, salt and pepper, and cook for 10 minutes. Wash the cabbage leaves and boil until tender. Put 2 Tbsp of meat mixture in each leaf and roll tightly. Secure each roll with a toothpick. Place in a saucepan and pour sauce over rolls. Cover pan tightly and cook slowly for 3 hours. Serve very hot.