Uses for leftover deli roast beef

If you've ever had leftover deli rare roast beef, heres one way I like to use it.
Slice some onion and put it in a skillet over low heat till it starts to wilt.
add the roast beef and some store bought bbq sauce,
stir it all together until its all heated.
Eat it on a brioche, challah or potato roll with some swiss cheese.
Poor mans bbq! mmmmm