For sauce, in a small bowl combine barbecue sauce, jalapeno pepper, and tahini. Transfer half of the sauce to another bowl for basting. Reserve remaining sauce until ready to serve. On two 8- to 10-inch skewers thread tomatillos, if using. Set aside. Brush both sides of turkey with basting sauce.
SANDWICH: On a large plate, place one focaccia loaf upside down. Arrange lettuce over focaccia and top with turkey, Basil Salsa and cheese. Place remaining focaccia loaf over top. To serve, slice into 6 wedges.