If using cooked beef, slice thin against the grain. If using uncooked beef, freeze for 30 minutes for easy slicing (if time allows). Slice against the grain in thin slices.
In a medium pot, boil water for egg noodles. Once boiling, cook egg noodles per package directions, until al dente.
Meanwhile, whisk together sour cream, onion soup mix, and flour in a small bowl. Add water and beef base, stir, and set aside.
Melt butter in a large skillet over medium high heat. If using uncooked beef, add half of beef to skillet. Cook for 2-3 minutes and remove.
Add mushrooms to skillet (and remaining uncooked beef if applicable) and cook for 5 minutes or until almost cooked.
Add all beef, garlic powder, and pepper to skillet and cook for one minute before adding sour cream onion soup mixture to the skillet. Bring to a boil, and add peas (if using). Cook for 2-3 minutes until thickens and peas are hot.
Add cooked egg noodles to skillet and stir. Ready to serve!
Notes
Freeze uncooked beef (if using) for 30-minutes so that it is easier to slice thin.
Use pre-made onion dip instead of sour cream and onion soup mix if needed.
To thicken gravy, mix 1 Tablespoon flour with 2 Tablespoons water to create a slurry, and slowly stir it into the pan while it is bubbling.