Start by slicing the chicken breasts into thin strips and marinate them with a teaspoon of soy sauce and a pinch of cornstarch for about 10 minutes. This helps them sear better and stay tender.
In a small bowl, whisk together the remaining soy sauce, rice vinegar, honey, sesame oil, and a splash of water to create your stir-fry sauce. Set it aside.
Chop the bell peppers into thin strips and cut the broccoli into bite-sized florets. Keep everything ready for quick cooking.
Heat your wok or skillet over high heat until it just starts to smoke, then add a tablespoon of oil and swirl to coat the pan.
Add the marinated chicken strips in a single layer and cook without moving for about 2 minutes, until they develop a golden, caramelized crust. Flip and cook for another 2 minutes until just cooked through. Remove and set aside.
Pour a little more oil if needed, then toss in the chopped vegetables. Stir constantly for 2-3 minutes until they are bright, slightly crisp, and fragrant with aroma.
Return the chicken to the pan, then pour in the prepared sauce. Toss everything together quickly, stirring for about 1 minute until the sauce thickens slightly and coats all the ingredients with a shiny, glossy finish.
Remove the stir fry from heat and let it sit for a minute to allow flavors to meld. Serve hot, garnished with sesame seeds or chopped scallions if desired.