Use knife to make one or two slices on the thick skin. Then prepare celery leaves, onion, and garlic. Chop them into small granules or pieces. Sprinkle some salt on knuckle. Then cover the knuckle with chopped vegetable mixture and wrap them tightly with a plastic outside. Put in the fridge overnight.
1. Take off the plastic wrap and wash off the vegetable mixture on the surface.
2. Steam knuckle for 50 mins.
3. Preheat oven to 220 degree C. Put steamed knuckle in oven and bake for 40 mins. You can move the knuckle to make the color evenly brown while baking.