Add all ingredients in the marinate/char siu sauce in a sauce pan, heat it up and stir-well until all blended. Transfer out and let cool.
Rub the ribs on both sides with the chopped garlic. Marinate the ribs with 2/3 of the marinate sauce for 8 hours or overnight in the refrigerator.
Preheat the oven to 325 degrees F. Line a large baking sheet with heavy aluminum foil, lay the ribs on top, and tightly cover with foil. Roast for 2 hours.
Preheat the grill and remove the ribs from the oven and uncover. Transfer the ribs to the hot grill and grill over direct heat for 5-10 minutes or until the surface slightly charred to your liking. Brush both sides of the ribs with the remaining char siu sauce plus some oil while grilling. Serve hot.