In a medium size bowl, combine the ingredients for the marinade and stir. Add the chicken pieces and stir well to ensure proper coverage. Let the meat marinate for about 10-15 minutes at room temperature.
Heat 2 tablespoons of peanut oil in a wok over high heat, until the oil is about 300F. Place the chicken in a single layer and fry for about 1 minute, until nicely caramelized. Flip the chicken pieces over to the other side and cook for another minute. Continue frying, stirring frequently, until the chicken is just done, about 2-3 minutes. (I like using my instant read thermometer to check for doneness and pull the chicken when it hits 160F internal temperature). Transfer the chicken to a platter, spread out and set aside.
In the same wok, heat another 1 tablespoon of peanut oil. Add the garlic and the ginger and stir fry for about 30 seconds over high heat, until slightly browned and fragrant. Now add the bell pepper, broccoli, red onion and stir fry for about 3 minutes, until the veggies have softened up and look slightly charred. Add the Thai chiles and stir fry for 30 seconds. Return the chicken to the wok, add sesame oil, scallions and stir well. Taste and adjust salt to taste. Continue stir-frying until the chicken is sizzling and fragrant, about a minute. Remove from heat and serve immediately with steamed rice or any other side of choice.