Method 1:
The pork seller said, don't cut open the original pig lungs, flush them through the water pipe, and then grab the lungs with your hands to squeeze out the water. Repeat this for many times until the pig lungs are clean, and the whole process takes about half an hour.
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Method 2:
With the help of starch, the dirty things are adsorbed. I didn't wash it myself. Maybe I cut the pig's lung and pressed it with powder, and repeated it many times.
Method 3:
A friend said, boil water in a pot, put the lungs in after boiling, and the big trachea extends outside, and the pig lungs contract when heated, and they will spit out the dirty things from the trachea themselves.