In a large skillet over medium heat, saute all the mushrooms with the onion, garlic cloves and 2 tablespoons of broth for 8 minutes or until the onions are soft.
Remove the mushroom-onion mixture from the skillet and set aside.
Lightly brown the flank steak in a skillet for about 5 minutes.
Add the remaining broth, ketchup and garlic powder; cover and let simmer for 10 minutes.
Return the mushroom-onion mixture to the skillet; add the Tofu Sour Cream and mix well.
Bring to a boil and cook for about 1 minute.
Serve over cooked spaghetti squash.