Place chicken cubes in a large mixing bowl and toss with cornstarch, salt, and pepper until evenly coated.
In a separate medium bowl, whisk together orange juice, orange zest, soy sauce, honey, rice vinegar, minced garlic, ginger, and red pepper flakes to create the sauce glaze.
Heat avocado oil in a large non-stick skillet or wok over medium-high heat.
Add the chicken to the skillet in a single layer, cooking for 6 to 8 minutes while turning occasionally until all sides are golden brown and cooked to an internal temperature of 165°F.
Pour the sauce mixture over the cooked chicken in the skillet.
Cook for an additional 2 to 3 minutes, stirring constantly, until the sauce reduces and thickens into a glossy glaze that adheres to the chicken.
Remove from heat and stir in the toasted sesame oil.
Garnish with sliced green onions and serve immediately over steamed brown rice or cauliflower rice.