Arrange the oven rack in the top third of the oven and preheat to 425°F.
Place the chicken thighs on a large sheet pan. Add the avocado oil, sesame oil, tamari, sriracha, honey, garlic, ginger, orange zest, orange juice, and five-spice powder. Using your hands, massage the sauce into the chicken so it’s well coated, about 2 minutes.
Add the Brussels sprouts to the same pan, season with salt and pepper, and toss everything together until the sprouts are evenly coated in the sauce. Arrange the chicken and sprouts in a single layer, making sure the chicken isn’t resting on top of the sprouts.
Bake for 25 to 30 minutes, flipping the Brussels sprouts halfway through, until the chicken is golden brown and the internal temperature reaches 165°F, and the sprouts are tender and caramelized around the edges.
Remove from the oven and let rest for 5 minutes until the juices settle. Spoon the pan juices over the chicken. Garnish with sliced green onions and sesame seeds.
To serve, spoon the cooked rice into a shallow bowl. Arrange the chicken and Brussels sprouts over the rice and spoon the pan juices all over. Finish with a little more sriracha, if desired, and enjoy!