Prep the chicken. Pat the chicken dry and cut into bite-size pieces if using breasts. Dry chicken browns better and helps the sauce stick.

Make the marinade. In a bowl, whisk soy sauce, honey, brown sugar (if using), rice vinegar, garlic, ginger, sesame oil, black pepper, and red pepper flakes. Stir in 2 teaspoons cornstarch until smooth.

Marinate briefly. Toss the chicken with half the marinade. Let it sit for 15–30 minutes at room temp, or up to 4 hours in the fridge. Reserve the other half of the marinade for the pan sauce.

Heat the pan. Set a large skillet over medium-high heat. Add oil and swirl to coat. You want it hot enough to sizzle on contact.

Brown the chicken. Add chicken in a single layer. Don’t crowd the pan; cook in batches if needed. Sear 3–4 minutes per side until lightly browned and mostly cooked through. Transfer to a plate.

Build the sauce. Pour the reserved marinade into the same pan. Add water or stock. Bring to a simmer, scraping up browned bits for extra flavor.

Thicken to sticky. Stir the cornstarch slurry (1 teaspoon cornstarch mixed with 1 tablespoon water). Drizzle it into the simmering sauce, stirring. Cook 1–2 minutes until glossy and thick enough to coat a spoon.

Glaze the chicken. Return chicken and any juices to the pan. Toss to coat, and simmer 2–3 minutes until the sauce clings and the chicken is cooked through.

Finish and serve. Turn off the heat. Sprinkle with scallions and sesame seeds. Serve immediately over rice with your favorite greens.