Oh, this is my kind of thread.
Montreal has an amazing scene for italian food. There's a place that makes the best sandwiches I ever had not far from my place. I've isolated the secret ingredient.
I now use it in my sandwiches and it changes everything: giardinera.
Basically pickled greens. Salad, carrots, cucumber, onions, peppers, name it.
It makes your sandwich not dry (I don't think wet sounds appetizing), it adds color, texture and the vinegary compliment whatever meat/cheese combo you get. Bonus points for some Peperoncino too, they're delicious.