In a large bowl, combine soy sauce, honey, brown sugar, sesame oil, garlic, ginger, and gochujang. Add the chicken thighs and ensure they are well-coated in the marinade. Cover and let it marinate in the fridge for at least 30 minutes (or up to overnight for deeper flavors).
Preheat your oven to 400°F (200°C). Arrange the marinated chicken thighs on a baking sheet lined with parchment paper. Pour the remaining marinade over the chicken.
Bake in the preheated oven for 25-30 minutes, or until the chicken is cooked through and has a nice caramelized glaze.
While the chicken is baking, mix the cornstarch and water in a small bowl to create a slurry. Once the chicken is done baking, remove it from the oven and transfer the excess sauce to a saucepan. Bring the sauce to a gentle boil and whisk in the cornstarch slurry. Simmer for 2-3 minutes until the sauce thickens.
Brush the thickened sauce over the baked chicken thighs and return to the oven for an additional 5 minutes to caramelize the glaze.
Once done, remove the chicken from the oven, let it rest for a few minutes, then slice it or serve whole. Garnish with sliced green onions and sesame seeds before serving.
Notes
For deeper flavors, marinate the chicken overnight.