I made this spicy horseradish mayo to go with my version of a Reuben sandwich, The Ruby. (my daughters name is Ruby, so naturally this name came to mind) The Ruby Sandwich consists of homemade corned beef, Swiss cheese, sweet and sour caramelized onions and a very generous spreading of horseradish-caraway mayonnaise.
I could give you instructions on how to make your own mayonnaise from scratch, but that isn't what I did. I just stirred in extra flavor to a good quality store brand. But I enjoyed the flavors so much I think I may have to remake the recipe from scratch!