In a large mixing bowl or glass measuring cup, add all the ingredients except the chicken and whisk until well combined.
Arrange the chicken thighs in a baking dish and pour the sauce over them.
Mix the sauce in with the chicken, making sure it goes under and around every single piece. Cover with plastic film and refrigerate overnight.
Preheat the oven to 350F and bake the chicken for 45 minutes, basting the meat with the sauce from time to time. Then, set the oven to broil and let the chicken brown / caramelize for 8-10 minutes.
Spoon sauce over the thighs, garnish with sliced green onions and more crushed dried chilis, if desired, and serve.