Blanch the fat in the boiling water for 2 minutes. Then transfer out and wash completely.
Add a small bowl of water into the wok and put the fat in. The water can prevent the fat from being burned. Simmer with medium heat and turn to small heat when the water is boiled away and then the fat begins to melt down. At the same time, keep stirring the fat so that the fat can be heated evenly. I will also recommend adding two stalks of scallion and several pieces of ginger.
Scoop the oil out when there is enough oil rendered. Filter the impurities out with a strainer.
Continue heating until the cracklings begin to turn golden brown.
Filter the cracklings and impurities out, pour the oil into a jar, and wait for the lard to cool down.
Video
Notes
Note 1: If you want the lard to be more suitable for deep-frying, stir-frying, or many traditional Chinese recipes, you can continue heating while the cracklings becomes slightly brown like me. For pastry usage, stop as long as the oil is separated, otherwise, the color might be influenced slightly. Do not forget the cracklings. You can return them back and add some salt or they can be stir-fried with cabbages or carrots.