Salt water soaking. Oysters are a kind of marine shellfish that can be farmed in the natural ocean, so many oysters contain more sediment and it is recommended to soak them first.1. Prepare a pot of water with a little bit of salt and a few drops of sesame oil.2. Put the oysters into the brine with a slightly smaller amount of water than the oysters.3. Let them stand for about 6 hours to let the oysters discharge the sediment in their bodies. In fact, oysters have already gone through the process of spitting out sand from the purification tank before leaving the factory, in other words, the oysters you buy are already relatively clean. Algae inside the shell can be brushed. It's cleaner when you cook it. The black stuff inside the oyster meat is the oyster's gut mass, which should contain a small amount of feces, but most people don't remove that part when they eat it. You can also take it out and eat it if you care.