Preheat a large skillet with the butter and brown the beef strips.

Save 1/3 cup of broth and use remaining broth in skillet with browned beef. Next add ketchup,salt,garlic and heat to a boil. After it comes to a boil reduce heat to a simmer and cover for 10 minutes.

Stir in mushrooms and onion and cover and simmer 5 minutes.

While that is cooking shake the leftover 1/3 cup of broth with the flour in a bowl w/lid.

Then gradually add the mixture to the skillet bring to a boil and stir for 1 minute.

Reduce heat to medium and add the sour cream for an additional 5 minutes and serve!