Pour the coconut milk, soy sauce, and vinegar into a large, lidded skillet and toss in the peppercorns, bay leaves, garlic, and chilies (if using Bring to a simmer over medium-high heat. Add the chicken pieces. Snuggling them into a single layer, the sauce should come about three-quarters of the way up the pieces (If it doesn't, add more water)
Return the sauce to a simmer, then cover the pan and reduce the heat to maintain a gentle simmer. Cook the chicken until the meat is very tender,
Remove the chicken pieces and continue simmering the sauce, over medium-high heat until it reduces by half and the sauce thickens a little/turns syrupy/coats a spoon, about 5 minutes. The flavor should be concentrated but not overpoweringly salty/sour.
Serve the chicken with cooked rice. Spoon sauce over the dish. You can also add some cilantro or green onions. Enjoy