I have made a huge stride in my never-ending quest for the perfect sandwich.
First you take a green pepper and a sweet onion......slice them as thin as possible (I use a mandolin slicer).
Now....in a bowl, toss them in a little red wine vinegar and olive oil.
Add a little basil, oregano, and red pepper flakes.
Let this marinate for a while and heap it upon your meat and cheese. It really pushes the sandwich over the edge and is healthier than a dose of mayo.
This relish lasts a few days in the fridge.