Apologies if I missed it, but a good Amish-style horseradish is seldom remiss.
I like some nice thin sliced red onion on mine. Balsamic vinegar is good, too.
Horseradish sauce. Go to Quizno’s and heist a little container of their sauce when they ain’t looking. Tasty.
I love pesto in sandwiches. Then olives, salami and rocket (I think you guys call it arugula), and some tomatoes or sundried tomatoes, all on a fresh ciabatta loaf and I’m in heaven.