Finely chop the onion and grate the carrot. Fry them in vegetable oil in a frying pan until half cooked. Add the finely chopped cabbage to the same frying pan and stew all together for about 30 minutes, pouring in half a glass of water and covering with a lid. Add salt and pepper to taste. Boil rice in salted water, and when ready, drain the water. Mix the forcemeat with the egg, boiled rice and stewed vegetables (cabbage, onion and carrot). Salt and pepper the forcemeat to taste. Make galumpkis (cabbage rolls) with this stuffing, place them in hot oil in a frying pan and fry on all sides under a high heat (until golden brown, and not until done). Pour the sour cream and tomato paste mixture into the frying pan with the already fried cabbage rolls, cover and simmer for 40 minutes until done. When ready, dish up having sprinkled with greens (optionally).