Fill a large pot with water and a small amount of salt. Bring it to a boil.
Add the egg noodles to the boiling water and cook them until they are tender but still slightly firm, which should take around 7 to 9 minutes. Once cooked, drain the noodles.
Meanwhile, on medium-high heat, heat a large skillet. Add the ground beef to the skillet and cook it while stirring until it turns brown and crumbly, which should take around 5 to 7 minutes. Remove any excess grease from the skillet.
Season the cooked ground beef with Greek seasoning, salt, and pepper.
In a separate skillet, heat the vegetable oil on medium heat. Add the mushrooms to the skillet and cook them while stirring until they become tender, which should take around 5 minutes. Add the cooked mushrooms to the ground beef.
Stir the sour cream into the ground beef and mushroom mixture. Cook and stir the mixture until it becomes hot, which should take around 5 minutes.
Serve the ground beef and mushroom mixture over the cooked egg noodles.