Grab your box of mushrooms and remove the stems from the heads. Also don't forget to wash them too so you wont get poisoned :D
Once you have done that, you can start slicing thin sheets of mushrooms out.
Take the onion out (preferred white onion) and start cutting them into thick pieces.
last but not least of prep, cut the meat into thin strips not too thin, but not too thick.
Add butter or margarine to the skillet or pan and spread it evenly.
once the burner is heated up to about half way to high, turn it down to medium or a little after. Start with the mushrooms
gently scoop the veggies around the pan so they all get evenly cooked. 2nd, add the onion
a few minutes after the onion gets roasted a little, add the meat. This is the part where you will want to nonstop mix.
while that cooks for 3-5 minutes you will want to start adding your noodles to a 3/4 full pot of water. Boil for 8-10 minutes
once the meat is almost cooked through add the cornstarch or flour to the meat. On the side add the cup of hot water and add the cube of beef flavoring
once thickened add the sour cream until it looks something like this.
Strain the noodles once tender and serve on a plate in which you will be adding the toping