Pat the chicken dry with paper towels. Season both sides with salt and pepper.
Heat the butter in a large skillet over medium heat. Sear chicken for 5-7 minutes per side, until golden brown and cooked through. The internal temperature should reach 165 degrees F (74 degrees C).
While the chicken is cooking, whisk together the olive oil, coconut aminos, honey, apple cider vinegar and red pepper flakes in a small bowl.
Reduce heat to low. Add the garlic to the center of the pan and cook, stirring, for 30 seconds. Add in the sauce and stir well. Bring to a simmer, then let the sauce cook down for about 5 minutes, stirring occasionally, until thickened.
Remove from heat. Garnish with sesame seeds and green onion if desired. Spoon remaining sauce over the chicken when serving.