In a bowl, whisk together hoisin sauce, soy sauce, brown sugar, honey, five-spice powder, garlic,ginger, and red food coloring if using.
Place ribs in the slow cooker and pour sauce mixture over them, coating evenly.
Cover and cook on LOW for 8 hours or overnight until ribs are very tender.
Preheat grill to medium-high heat. Remove ribs from slow cooker and let excess sauce drip off.
Grill ribs for about 2 minutes per side until lightly charred and smoky.
Reserve the liquid from the slow cooker and reduce on low until thick and smooth (add 1 tsp of cornstarch if needed to thicken)
Spoon glaze on ribs, slice, garnish and serve hot.