If you don't have a mortar and pestle at home, use knife to crush black pepper and coriander seeds to smaller pieces
Sprinkle salt onto duck leg and massage
Sprinkle black pepper, bay leaves, and coriander seed onto the duck leg
Put the seasoned duck legs to a zip bag or a bowl. Seal it and put in refrigerator to cure overnight
Take the overnight cured duck legs from refrigerator and rinse with water to remove salt, and other seasonings.
Put the garlic and ginger into the cast iron pot and put duck legs into the pot
Turn on the oven and set temperature to 220F. Put the pot, with lid, into the oven
After 2 hours, take the pot out and flip the duck legs, put the pot back into the oven
Keep the pot in the oven for another 2 hours
If you decide to finish the dish right after the above step, raise your oven temperature to 400F. Put the duck legs on a baking pan.
Bake the duck legs for 25-30 mins. Switch to broil. Watch closely when using broil. Take the pan out of the oven when the duck legs turn dark brown.