Steak, redux

I made my caramelized onion, flank steak, and blue cheese on baguette sandwich for lunch today. I added a little mayo. It was very good--it would have been better had I toasted the bread. And maybe added a bitter green--like arugula. Or, as they call it in the UK, rocket!
We're working ourselves up for the hot pastrami. Good suggestion on the spicy mustard, Tony, but I think I'm going to kick it old school with the yellow. This baby's about nostalgia for me. Angie will go with the spicy, I'm sure.
Now to find the perfect bun.....