Beef Stroganoff

1 pound ground beef
1 small can sliced mushrooms (if desired)
2 tbsp butter or margerin
3 tbsp flour
1 tbsp tomato paste
1 can beef broth
1 cup sour cream

Brown beef and mushrooms.  Add butter.  Stir until melted.  Blend in
 flour.  Add tomato paste and stir.  Gradually add soup.  Cook until
 thick.  Heat several minutes after thick.  Add sour cream and stir. 
 Turn down heat once sour cream is added.  Serve over noodles or rice.