Preheat the oven to 450°F (230°C). Line a large rimmed baking sheet with parchment paper or lightly grease it with olive oil.
Place the cubed chicken on one side of the prepared baking sheet.
Season with garlic powder, black pepper, and chile flakes.
Sprinkle the flour over the chicken and toss until the pieces are lightly coated.
Drizzle approximately 2 tablespoons of olive oil over the chicken and toss again.
Spread the chicken into a single layer, leaving some space between the pieces.
Arrange the broccoli florets or chopped asparagus on the other side of the pan.
Drizzle the vegetables with the remaining olive oil and season lightly with salt and black pepper.
Roast for 10–15 minutes, or until the vegetables are tender and the chicken is nearly cooked through.
Meanwhile, prepare the sauce. In a medium bowl, whisk together the tamari or soy sauce, lemon juice, honey, grated garlic, gochujang, green onions, and toasted sesame oil.
Remove the baking sheet from the oven. Transfer the cooked vegetables to a serving dish and keep warm.
Pour the prepared sauce over the chicken and toss carefully until every piece is coated.
Return the chicken to the oven and bake for approximately 5 additional minutes, until the sauce becomes glossy and clings to the chicken.
Make sure the chicken reaches a safe internal temperature of 165°F (74°C).
Remove the 30 Minute Honey Garlic Chicken from the oven and sprinkle with additional green onions and toasted sesame seeds.
Serve warm with the roasted vegetables and rice if desired.