Start with the boneless, skinless chicken thighs. Season with salt and pepper and coat on both sides with cornstarch. My favorite shortcut is to add the chicken, salt, and pepper to a large zip-top bag and give it a good shake. Then add the cornstarch and shake again until every piece is evenly coated.
Heat 2 Tablespoons of sesame oil in a 12-inch skillet over medium-high heat. Add the chicken and sear for 8-10 minutes until cooked through, flipping halfway for each side to brown evenly. (Chicken is considered done when an instant read thermometer reads the center of the thickest part as at least 165°F.) Remove the chicken and set aside.
Reduce the heat to medium heat. Into the skillet, whisk together the remaining sesame oil, rice vinegar, soy sauce, and garlic for 1 minute, scraping up the bits of chicken from the bottom. Then, whisk in the honey. Let simmer for 2-3 minutes. (If adding red pepper flakes, add during this step.)
Return the chicken to the pan and simmer until the sauce thickens slightly, flipping the chicken to coat both sides in the honey garlic sauce. Let simmer for an additional 2-3 minutes.
Serve over rice with broccoli or your favorite vegetable. Garnish with extra sauce and sesame seeds, if desired.
Leftovers keep well in the refrigerator for a few days. You can reheat on the stove over medium heat or in the microwave.
Notes
Freezer Instructions: You can make the sauce ahead of time. Allow to cool completely, then freeze for up to 3 months. Thaw overnight in the refrigerator. I don't recommend coating the chicken in cornstarch ahead of time.
Chicken: You can make this dish with boneless, skinless chicken breasts, but I use chicken thighs because they not only cook faster, the fattier meat adds more flavor. If you opt to use chicken breasts, I recommend pounding them to an even thickness before cooking, to ensure they cook evenly.