Here's what I put on the sandwich:
Pre-seasoned and -grilled tofu cutlets*
Follow Your Heart mozzarella
(on Jewish rye)
* To prepare the tofu I mixed up about a tablespoon of BBQ sauce with 1-2 Tbsp. tamari and 1-2 Tbsp. balsamic vinegar. Then I just dipped each 1/2" slice of tofu in that (turn to coat all sides) and let it sit while I heated the grill. Grill until those lovely marks appear on the top, then load up your sandwich and grill the whole thing. Yum! Fast, too.
I can't wait to throw a portabello on this thing...