Season beef cubes with salt and pepper.
In a large skillet, heat butter over medium heat.
Add beef and cook until sides are brown.
Move beef to the side of skillet and add onion; cook until softened, approximately 3-5 minutes.
Slide onions to the side of the skillet with the beef. Add flour and cook for 1 minute.
Pour in beef consomme and mushrooms. Stir to combine while sauce thickens.
Reduce heat and simmer, covered, for 1 hour.
When meat is tender, cook noodles according to package; drain.
Serve stroganoff over cooked noodles.