In a large bowl, whisk together soy sauce, oil, brown sugar, ketchup, garlic, turmeric, and coriander. The mixture should look smooth and well combined. This marinade gives the chicken deep flavor and beautiful color.
Add the chicken pieces to the bowl and coat them evenly. Cover and refrigerate for at least 4 hours. Longer marination gives richer taste and juicier results.
If using wooden skewers, soak them in water for 30 minutes. Preheat the grill to medium-high heat. Lightly oil the grill grates to prevent sticking.
Place the chicken pieces onto skewers, leaving small gaps between pieces. Grill for 3–6 minutes per side depending on thickness. Cook until slightly charred and fully cooked inside.
In a saucepan, combine coconut milk, peanut butter, brown sugar, curry paste, sriracha, soy sauce, and lime juice. Simmer gently while stirring until smooth and slightly thickened. Adjust consistency with a little water if needed.
Remove chicken from grill and let it rest briefly. Serve warm with peanut sauce on the side for dipping or drizzling.