Combine the chicken broth, orange marmalade, soy sauce, garlic powder and red pepper flakes in a small bowl, then whisk to combine. Set this aside for later.
Heat a wok or large skillet over medium-high heat. Add 1 tablespoon of oil to the pan and cook the peppers and onions for 2 to 3 minutes, stirring frequently. Remove the pepper and onion from the pan and set aside.
Heat the remaining tablespoon of oil in the wok or skillet and toss the bite-size pieces of chicken in the cornstarch, shaking off the excess.
Add the chicken to the pan, being careful not to overcrowd the pan (I like to do this in two batches).
Brown the chicken on all sides, about 2 to 3 minutes per batch. Once all the chicken is cooked, add the vegetables back to the pan, then stir in the sauce and heat it through until it bubbles and thickens.
Garnish with sliced green onions and sesame seeds, if desired. Enjoy!