Place the chicken breasts between two pieces of plastic wrap and pound to about 3/4 inch thick. Remove the plastic wrap, then combine the chicken and teriyaki marinade in a large freezer bag and refrigerate 1 to 2 hours.
Preheat a grill to medium high. Mix the mayonnaise, Sriracha and scallions in a bowl; season with salt and pepper.
Grill the pineapple slices until charred, about 2 minutes per side. Remove the chicken from the marinade and season with salt and pepper. Lightly oil the grill grates with the vegetable oil using a paper towel or silicone brush. Grill the chicken until cooked through, 5 to 7 minutes per side. Coat in the toasted sesame seeds and then thinly slice on the diagonal.
Sandwich build: Split the baguette in half lengthwise and lightly toaston the grill. Schmear the mayo mixture on the baguette top. Layer the chicken on the baguette bottom. Top with the grilled pineapple, cabbage and the baguette top. Cut into individual sandwiches and serve with more teriyaki marinade.
Photograph by Kang Kim
Recipe courtesy Jeff Mauro for Food Network Magazine