When steak has been cooked and removed to a hot platter, add ketchup and sherry to drippings in broiler pan.
Then add Worcestershire sauce to taste (1/2 teaspoon or more), stir well, and place under broiler. Leave door open so that you can watch how sauce is cooking. It should be bubbling in 1 or 2 minutes.
Remove from stove and pour over steak.