Fill a large pot halfway with water, cover, leave it to boil over high heat.
Meanwhile, crumble the beef into a large saucepan, add chopped onion and garlic powder. Sauté on medium-high until the beef is browned and the onion is soft. If the beef lets off more than 3 tablespoons of fat, drain it carefully. A little bit of fat will help the dish, while too much will make it greasy.
Add the mushrooms, consommé, salt, and pepper to the beef & onion mixture. Simmer on low for 10 minutes.
When the water is boiling, add the noodles and cook until they are soft but not soggy. Drain carefully, leaving the noodles in the large pot.
Add the ground beef & mushroom mixture, cream of mushroom soup, and sour cream. Mix gently until everything is combined. Let it sit, covered, for about 5 minutes before serving, giving all the flavors some time to blend.
This dish is best served on a plate since the flavors really develop as it cools. Taste before seasoning, then sprinkle sparingly with salt and pepper as desired.