Prep the chicken: Pat chicken dry and cut into bite-size pieces.
Season lightly with salt and pepper. This helps it brown nicely and taste seasoned all the way through.
Make the sauce: In a small bowl, whisk together honey, soy sauce, minced garlic, rice vinegar, sesame oil, and red pepper flakes if using. Taste and adjust—add a splash more soy if you want it saltier or a touch more honey for extra sweetness.
Cook the green beans: Heat 1 tablespoon oil in a large skillet over medium-high.
Add green beans with a pinch of salt. Cook, stirring occasionally, until bright green with some blistered spots and crisp-tender, about 4–6 minutes. Transfer to a plate.
Sear the chicken: Add another tablespoon of oil to the skillet.
Add chicken in a single layer. Let it sear undisturbed for 2–3 minutes, then stir and cook until mostly cooked through and lightly browned, about 5–7 minutes total.
Add the sauce: Pour the honey garlic mixture over the chicken. Stir to coat and bring to a lively simmer.
If you like a thicker glaze, stir in the cornstarch slurry and simmer 1–2 minutes until glossy.
Return the green beans: Add the cooked green beans back to the skillet. Toss everything together and cook 1–2 more minutes so the beans are hot and coated in sauce.
Finish and serve: Turn off the heat. Sprinkle with sesame seeds and green onions if you like.
Serve over hot rice or noodles, spooning extra sauce on top.