I am from Salt Lake City - relocated to New Mexico 2 years ago. "Burger Sauce" also known as "Fry Sauce" is well known, used, available at a lot of restraunts and fast food joints. That is not the case here. People look at me like I'm a crazy person when I order a side of mayo (so I can make my Burger Sauce when we eat out).
If you haven't tried this, you should...
1 c Hellmann's/Best Food's mayonnaise
1/2 c ketchup
Mix the mayo and ketchup together until they are well incorporated. Add garlic powder, salt and pepper to taste. Spread on your burger bun and enjoy that goodness...
We also use this sauce with our fries instead of ketchup.