Work in batches to fry the mushrooms in a neutral tasting oil. For me it's expeller pressed safflower oil. When they are done set them aside.
After the mushrooms are cooked brown the Beyond Beef. While the "beef" is cooking keep breaking to up into smaller pieces.
When the "beef" is brown add you onion and cook until they are soft. Remove from the pan and set aside.
With your pot on medium heat add two Tablespoons of oil and two Tablespoons of flour. Stir to combine. Keep slowly stirring until the flour just starts to turn color.
Add the veggie stock, keep stirring to combine and bring to a boil. Add the "beef" salt, pepper and garlic powder. When it comes back to a boil add the noodles stir and cover.
Keep cooking until the noodles are done. Every minute or so remove the lid and give them a stir.
When the noodles are done remove from the heat and add the mushrooms and stir. Then add in the plant based sour cream.