Chop the onion and fry briefly in hot fat. Off the flame, sprinkle with paprika and immediately pour a little soup or water. Put the lid on and saute on low heat until the onion pieces are almost cooked. Remove lid, increase heatand give the onion mixture some color. Salt and pepper the lamb cutlets and add to the onion pieces. Pour in some lamb stock or beef broth and simmer the meat until tender, about 1 1/2 hours. Once the lamb is cooked, lift out and keep warm. Mix sour cream with flour, thicken the bell pepper sauce with it and let it boil down on low heat for a few more minutes. Put the meat back in and serve with chipotle or roasted potatoes, lettuce and warm mustard pickles.