Line a baking sheet with parchment paper. Set aside.

In a small bowl, combine the mayonnaise and balsamic glaze. Mix together then set aside.

In a bowl, combine ground chicken, yogurt, mustard, salt, pepper and onion powder. Mix to combine thoroughly. Form into patties (this recipe makes 6) and place each patty on the baking sheet. Place chicken patties in the freezer for 15 minutes. (this step is very important, as freezing them briefly, then placing them directly on the grill from the freezer will keep the patties in tact while grilling.)

While the chicken patties are in the freezer, prepare the coals for the grill.

Once the coals have turned white, oil the grill grates with an oil coated paper towel. Place chicken patties directly from the freezer on the grill and close the lid. Let cook for 6 minutes, then turn and cook for another 6 minutes or until the internal temperature registers 165 degrees.

Take chicken burgers off the grill and let them sit for 5 minutes.

Toast the brioche buns, keeping a close eye on them not to burn. Coat each side of the bun with the balsamic glaze mayo. Assemble the burger, adding tomato and lettuce if desired.