Cut stew meat and coat with salt and pepper. Put in Crock-Pot with onion. Mix garlic salt, Worcestershire sauce, bouillon and ketchup. Pour over meat and cook on low for 6 - 8 hrs.
Turn Crock-Pot to high and add the mushrooms. Dissolve the flour in a small amount of water and stir with a whisk. Add it to the Crock-Pot and stir until blended. Cook for 15 minutes or until slightly thickened. Stir in sour cream and turn off heat. Serve with noodles or rice.
*Optional: Instead of using 1 1/2 cups of beef bouillon, use 1/2 cup wine and use only 1 cup beef buillon.