My Dad's twist on Stroganoff

Hi my Dad is a great cook and I kept trying to get my stroganoff to taste like his and it just wasn't working. I finally asked what he added to his and I couldn't believe it. His secret ingredient was ketchup. I love the extra flavor so I thought I'd share his recipe.

1 pound beef tenderloin of sirloin steak
2 tablespoons all-purpose flour
1 8-ounce carton of sour cream (our less if you don't want it quite so rich)
2 tablespoons beef bouillon
1-2 tablespoons of ketchup (depending on taste)
2 tablespoons margarine or butter
1 1/2 cups mushrooms (if you and stand those)
1/2 cup chopped onion
garlic to taste
2 cups hot cooked noodles

Thinly slice meat across the grain into bite size strips. In a large skillet saute meat, mushrooms, onions and garlic in the margarine or butter. Cook till meat is done. Add remaining ingredients to skillet and cook on medium heat till bubbly. Cook one more minute. Serve over noodles