In the marinade bowl, move all the seitan to the side, and add the sliced scallions, coating them in sauce. So your bowl should be one side seitan and one side scallion, more or less.
Form the rolls on a dinner plate, to avoid messiness. Take a slice of marinated seitan and place it on a dinner plate. Place 4 or 5 scallions across, so that scallions will poke out of the ends an inch or so. Now roll the seitan around the scallion, and secure it with a toothpick or two. Make sure that the toothpicks are going in the same direction, so that you’ll be able to grill them without toothpick interference.
Once rolls are formed, heat the grill over medium heat. Spray or brush grill with oil, and cook rolls until grill marks appear. I did 8 at a time, and it took about 4 minutes on my indoor cast iron grill. Use a metal spatula to get under the rolls and flip them, spraying more oil as necessary. Cook on the other side until grill marks appear.
Transfer rolls to a serving plate. When ready to serve, drizzle with leftover marinade, and some Sriracha (if you like it spicy, it’s ok to leave off) and sprinkle with toasted sesame seeds. Serve!