Combine all ingredients except pork belly in a bowl and whisk to combine. Reserve half of marinade for later.
Slice pork belly into 1/2 to 3/4 inch slices and add to marinade. Marinate for 3 hours or overnight. Drain and discard marinade
Preheat grill to 350°F. Grill slices turning every 15 minutes or so.
Return slices to bowl of reserved marinade to coat and return to grill. Grill until internal temp is 190°F basting with marinade.
Garnish with sliced green onions and toasted sesame seeds. Serve with rice and baby bok choy.