In a small bowl combine brown sugar, honey, soy sauce, dry sherry, oyster sauce, five spice, garlic and red food coloring (optional) and mix until combined.
Cut pork horizontally into three long flat pieces. Place in a container or ziplock bag, pour marinade over pork. Marinade 24-48 hours for optimal flavor.
Preheat oven to 350 degrees. Cover a baking sheet with foil and place a cooling rack on top. Place pork on the rack. Bake for 25 minutes. Flip the pork and cook another 25 minutes.
While the pork is cooking, pour the reserved marinade into a saucepan and bring to a boil for 10 minutes. Reduce heat and whisk in cornstarch and water and simmer on low for another 10 minutes.
Remove pork from the oven and turn the oven to broil. Brush the pork with the thickened marinade and broil 5-6 minutes or until slightly charred. Turn the pork over and repeat. Pork temp should be 145-160 degrees.