Preheat oven to 200 degrees C
To make the sauce, whisk together chili sauce, soy sauce, garlic, fish sauce, ginger, lime juice and Sriracha in a small bowl; set aside.
Melt butter in a large oven-proof skillet over medium high heat. Add chicken, skin-side down, and sear both sides until golden brown, about 2-3 minutes per side. Stir in chili sauce mixture.
Place into oven and roast until completely cooked through, reaching an internal temperature of 165 degrees F, about 25-30 minutes. Then broil for 2-3 minutes, or until caramelized and slightly charred.
Serve immediately, garnished with peanuts and cilantro, if desired.
