Place one chicken breast at a time into a Ziploc bag and gently pound it to an even ½-inch thickness—just enough to tenderize without tearing the bag.

In a medium bowl, whisk together soy sauce, apple sauce, finely chopped onion, sesame oil, freshly grated ginger, brown sugar, minced garlic, a pinch of red pepper flakes (if you like a little heat), and sesame seeds. Set aside ¼ cup of this flavorful marinade, then pour the rest into the bag with the chicken.

Seal it up, give it a little shake to coat evenly, and let it marinate in the fridge for at least an hour to soak up all that delicious flavor.

Heat a grill over medium-high heat. Once hot, place the chicken on the grates and let it cook undisturbed for 2 to 3 minutes, or until it naturally releases from the grill.

Flip, spoon the reserved marinade over each breast, and grill for another 2 to 3 minutes, ensuring a beautifully caramelized exterior and juicy interior. Enjoy!