Ketchup, about 1 cup
Worcestershire Sauce, about 1/4 teaspoon
Horseradish (cream style, prepared), about 1 teaspoon
Lemon juiced, about 1/4 of lemon
I like mine hotter than my wife, so I add hot sauce (Texas Pete) to a separate serving for me.
You may want to adjust up/down the horseradish. It should be enough to have a kick to it, but not so much your nose is burning!