A special most places, a regular dish at Feelings. One of the primary ingredients in a good crab boil is mustard seed. I add extra. Plain old Zatarain's Creole mustard right out of the jar. This is a great condiment with all kinds of things.
Corned beef comes to mind.
Grilled sausage is another. Essential on a ham poor boy. This is closer to the French remoulade, but to my tastes not as good as the local red variety. It's little more than Creole mustard mixed with mayonnaise, plus perhaps a little Worcestershire, shallots, or whatever. A good sauce, though.