This is the steps I searched for. Although I am not very good at it, it can be made by following the steps.
Rinse the pig suet with running water and cut it into small pieces.
Add half a bowl of water.
Cook over high heat until the water dries up.
When the suet starts to come out of oil, turn down the heat to low and turn the pan over with a spatula from time to time.
Boil slowly until all the oil comes out and the oil residue turns golden.
Filter through a sieve and put the boiled oil into a container. After cooling down, add a little sugar and salt before solidification.
