Peel and chop onions. If large mushrooms are being used, slice into rather large slices. I prefer to use small mushrooms and leave the whole. Dredge beef cubes in flour and give them a light coating. Heat a large stewing pot and add olive oil. Brown beef cubes thoroughly in olive oil. Add onions, garlic and mushrooms and saute lightly. Add red wine (all) and enough beef stock to barely cover the ingredients. Add bay leaf (broken) and dill. Salt and pepper to taste. Add tomato paste. Cover and simmer, stirring occasionally, for about 2 hours or until beef is very tender. The cooking liquid will thicken from the flour in which you dredged the beef. The desired result is that the ingredients are coated with a thick gravy. If more liquid is needed during the cooking process, add additional beef stock sparingly. Be careful that you scrape the bottom of the pot when stirring to prevent flour from sticking and burning. Just before ready to serve, mix in 1.5 cups sour cream. Place into a casserole dish or tureen and garnish with sprigs of fresh dill. Serve with rice or buttered noodles.