Also, @pulykamell, this post from another thread suggests that mustard on burgers may have some north-south latitude correlation …
I just assumed so because once I move from Texas getting mustard on your burger was as rare hen’s teeth. A quick Google search seems to confirm it. Article in the Atlantic: And guess which state in America uses mustard on its burgers, to the exclusion of ketchup? No, not some liberal, elitist state like Taxachusetts. It’s Texas. City-Data: Krystal down here (Southern version of White Castle) only serves their burgers with mustard and a pickle. The Baltimore Sun: What’s with mustard on bur…