Pat chicken thighs dry, season with salt and pepper. Heat oil in a wide skillet over medium-high. Sear chicken 4–5 minutes undisturbed until deeply golden. Flip and cook 3–4 more minutes.
Char the Vegetables
In the same pan over high heat, add oil. Add broccoli and carrots in a single layer. Let sit undisturbed 2 minutes until the undersides char. Toss and cook 1–2 more minutes until tender with good color. Season with salt. Remove and set aside.
Build the Glaze
Reduce heat to medium. Add garlic and cook 20 seconds until fragrant. Add honey, soy sauce, rice vinegar, sesame oil, chili flakes, green onions, and stock. Stir and bring to a simmer. Let reduce 1 minute.
Stir the cornstarch slurry to recombine, then pour into the pan while stirring. The glaze will tighten and turn glossy in 20–30 seconds. Drop in the butter and dark soy sauce and swirl the pan until it melts and the glaze looks silky and lacquered.
Glaze the Chicken
Return chicken and veggies to the pan. Toss and spoon glaze continuously over each thigh until fully lacquered, 30–60 seconds. Remove the chicken and slice into bite-sized pieces.
Plate and Finish
Spoon rice into a wide bowl. Arrange broccoli and carrots around the rice. Lay sliced chicken on top so the caramelized surface faces up. Spoon remaining glaze generously over everything. Finish with scallions, sesame seeds, and chili flakes.
Notes
Char the vegetables in the same pan after the chicken. They pick up the fond and taste better for it.
Don't steam the broccoli. You want char marks and some bite, not soft and soggy.
Spoon the glaze over the rice and vegetables too, not just the chicken. Tt soaks in and gives the whole bowl color and flavor.
The cornstarch slurry tightens the glaze into a lacquer; the butter at the end emulsifies it into something silky and glossy that clings to every bite.
Be careful not to heat the sauce for too long after the cornstarch slurry is added. If heated for too long, the sauce will break and lose its thickness.