In a large non-reactive bowl, combine the vinegar, coconut milk, soy sauce, garlic, turmeric, bay leaves, chillies and pepper. Add the chicken and turn to coat, then cover with plastic wrap and leave to marinate in the refrigerator for at least 3 hours or overnight.
Transfer the chicken and marinade to a large, deep saucepan. Bring to the boil, then reduce the heat to low-medium and cook for 25 minutes, or until the chicken is cooked through. Using tongs, transfer the chicken to a bowl and cover to keep warm. Increase the heat to medium-high and cook the marinade mixture for 10 minutes, stirring occasionally, until slightly thickened and reduced. Discard the turmeric, bay leaves and chillies.
Return the chicken to the pan and warm through. Transfer to a serving bowl, scatter with extra chillies, if using, and serve with steamed rice.