Portion out some salt and cornstarch into separate bowls. The amount you need may be more or less
Rub the outside with some salt all over and then turn it inside out and rub with salt. Rinse it off with clean running water. You can cut off or pull off any excess fat or the lining of the stomach along the way if you see any
Apply some cornstarch and rub inside of the maw. Rub thoroughly. Rinse off with water and then repeat again until you don't smell any funky aroma. Turn the maw back inside out
Scald the cleaned pig maw:
Preheat a large pan or wok. Put the pig maw and let it scald for few minutes on the wok. There will be some milky brownish liquid oozing out. Let it scald for a good 5 minutes or so and then remove from the pan or wok. Discard the liquid
You can turn the inside out again to check. The inside shouldn't feel slimy anymore. You can use kitchen shears to trim off any excess fat if you like
Storing:
Once it has cooled down completely, wrap it up in several layers of cling wrap and put it inside a freezer bag. You can keep them frozen for about 1 month. Simply thaw overnight in the fridge when you are ready to use them in the recipe