Boil noodles as pakage directs, then drain. While noodles cook, prepare liver slivers: Dredge liver thoroughly in flour, melt butter in skillet over medium heat and brown liver. When juice beads begin to appear on the surface of the meat, turn to brown the other side. Do'nt overcook!
Remove meat to a dish. Saute onion in remaining butter in pan.until golden and soft. Remove and add to dish with liver. By now the noodles are done, so fry them in remaining butter until some are crisp. Turn off heat, add meat and onions, toss, and season to taste and serve immediately.