Make the sauce Whisk together honey, soy sauce, minced garlic, rice vinegar, cornstarch, and red pepper flakes in a small bowl until smooth. Set aside. Having the sauce ready before the chicken hits the pan matters because this recipe moves fast.
Prep and coat the chicken Pat chicken pieces completely dry with paper towels. Season with garlic powder, salt, and black pepper. Toss in flour until each piece is lightly and evenly coated. Shake off any excess - a thin coating is what you want, not a thick crust.
Sear the chicken Heat avocado oil in a large skillet over medium-high heat until shimmering. Add chicken in a single layer - do not crowd the pan. Cook undisturbed for 3 to 4 minutes until golden brown on the bottom. Flip and cook another 2 to 3 minutes. Work in batches if needed. Internal temperature should reach 165F. Remove chicken to a plate.
Build the sauce Reduce heat to medium. Pour the honey garlic sauce directly into the same pan. It will bubble immediately. Stir and scrape up any browned bits from the bottom - that is flavor going into the sauce. Let it simmer for 2 to 3 minutes until slightly thickened and glossy.
Coat the chicken Return the chicken to the pan. Toss to coat every piece in the sauce. Let it cook together for one more minute so the sauce clings and reduces slightly around the chicken.
Final check Taste the sauce. Adjust with a small splash of soy sauce if it needs more salt, or a teaspoon more honey if you want more sweetness. Both are easy to balance at this stage.
Serve Transfer honey garlic chicken to a serving plate or directly over rice. Spoon any remaining sauce from the pan over the top. Garnish with sliced green onions and sesame seeds if desired. Serve immediately while the sauce is sticky and glossy.