Always check with the seller when possible, on how many days you need to soak the sea cucumber as this depend on the size, the grade/quality of the sea cucumber you get
If you are soaking for several days, always change with fresh water every day until the end of the recommended soaking period. Make sure the sea cucumbers are completely submerged in the water. Cover them so no other particles will get in. Put them in the fridge during soaking period
After 4 days of soaking, they have soften considerably. I run my thumb up and down to get rid off the stuff inside the sea cucumber. You may need a knife or scissors if it's hard to do it with your hands. You may also need to scrap the outside of the sea cucumber to get rid of the extra "whitish" crust if any is present. Some variety doesn't have this whitish crust (like the one I'm showing in the video)
It had almost tripled or quadurpled in size at the end of the soaking period
Boiling (optional):
At the end of the soaking period, in my case, day 4, boil the sea cucumber for about 1 hour in a big pot with a lid on over low to medium heat and do not remove the cover
If you use a pressure cooker like I did in the video, I pressure cook on high pressure for 20 minutes
Throw away the water. If they are still hard, boil again with a fresh water until it is soft and bouncy (you can leave the lid out this time). Be careful not to over boil or it can turn into mush
How to store:
Let them cool down completely. Wrap them up individually in plastic wrap and place in freezer bag. They can be kept frozen for up to 2 months. Just thaw and proceed to cook with recipe or you can proceed to boil (instruction below)
You can wrap them with plastic wrap and freeze them if you are not going to use them soon. They can be freeze for 1 month
When ready to use them:
When ready for use, thaw them in the refrigerator overnight and then cut them into the desired sizes and proceed with recipe you plan to cook