In a mixing bowl, combine ground chicken, soy sauce, teriyaki sauce, brown sugar, garlic powder, onion powder, ground ginger, and black pepper. Mix well until all the ingredients are evenly incorporated.
Divide the mixture into 4 equal portions and shape them into patties. Make sure the patties are slightly larger than the burger buns as they will shrink slightly during cooking.
Preheat a grill or a frying pan over medium heat. Place the patties on the grill or pan and cook for about 4-5 minutes on each side, or until the internal temperature reaches 165°F (74°C).
While the patties are cooking, lightly toast the burger buns on the grill or in a toaster.
Once the patties are cooked, remove them from the heat and allow them to rest for a few minutes.
Assemble the burgers by placing a cooked patty on the bottom half of each bun. Top with lettuce leaves, sliced tomatoes, and sliced red onion. Add mayonnaise if desired.
Drizzle some additional teriyaki sauce over the assembled burgers, if desired.
Place the top half of the buns on each burger and serve immediately. Enjoy your homemade teriyaki chicken burgers.