Pat the chicken thighs dry and season both sides with salt and black pepper.
Heat the olive oil in a large skillet over medium-high. Sear the thighs 5-6 minutes per side until golden and cooked through (165°F), then transfer to a plate.
Lower the heat to medium, add the garlic and cook 30 seconds until fragrant; do not let it brown.
Stir in the honey, soy sauce, apple cider vinegar and red pepper flakes; simmer 2 minutes, scraping up the browned bits.
Whisk the cornstarch with 2 tbsp water, stir it into the sauce and simmer 1-2 minutes until glossy and slightly thickened.
Return the chicken to the skillet, spoon the glaze over and simmer 1 minute. Scatter with scallions and sesame seeds; serve with rice and steamed broccoli.