Mix chicken, fish sauce, and honey together in a bowl; cover with plastic wrap and refrigerate for at least 30 minutes.
Heat a wok or large skillet over medium-high heat; swirl in oil. Add red bell peppers, lemongrass, ginger, and garlic; cook until red bell pepper strips tender, about 5 minutes. Add chicken mixture; saute until chicken is no longer pink and the juices run clear, about 5 minutes.
Stir green onions, chicken broth, sugar, red pepper flakes, salt, and pepper into the wok. Simmer, uncovered, until sauce thickens, about 5 minutes.