Brown lamb slowly in butter, adding additional butter if needed; add onon and paprika. Saute 2 or 3 minutes, then add vinegar, salt and stock. Cover and simmer until meat is tender, about 45 minutes. Stir in sour cream and heat to serving temperature. Serve with Spaetzle or noodles. SPAETZLE: Mix eggs, salt and flour together to form a fairly stiff dough. Pat out into a rectangle about 1/8 inch thick on a damp breadboard. With a damp table knife, cut into strips 1 inch wide. Cut or pinch off 1 inch pieces and drop into a kettle of boiling, salted water. When the dough omes to the surface, they are done. Drain in a colander and quickly turn into a hot bowl or casserole. Sprinkle with butter or buttered crumbs; toss lightly and serve with any sauced meat dish.