Rub the clam shells together, and rinse them in water.
Set a colander inside a bowl. Add the clams and 3% salt water. Cover with a lid or something and leave for 1 hour to overnight. (Use a little more water in weight than the clams.)
The clams will all open up like this, which is fun.
It depends on the type of Manila clams you are using, but you'll see a lot of sand and dirt has dropped to the bottom of the bowl. It feels good to see it gone!
Rinse the clams again, and drain them for a while in a colander.
When they have drained and expelled the salt water, you can use them in any dish you like, safe in the knowledge that they're nice and clean.
A bonus recipe! Put the cleaned clams in plastic bags and freeze. You can use them as-is without defrosting in your recipes.
The main photo shows 500 g of clams with 500 ml of water + 150 g of salt. I froze half of them.
Whenever I see Manila clams on sale, or when they go on sale in the evenings near closing tiem, I buy a lot and freeze them.
One more! When you buy Manila clams, try shaking the packs. The ones that makes a heavy sound are healthy ones. If they make a light empty sound they're not that good.
You can treat surf clams (hamaguri) in the same way - they'll come out of their shells like this!
Story Behind this Recipe
If you just guesstimate things when de-sanding clams and fail, it's a shame. So I've made this a foolproof recipe (?) for everyone. Please use this method and enjoy creating lots of Manila clam recipes!
I usually do this at night, drain it in the morning and freeze the clams. If you have clams stocked in the freezer, you can make pasta, soup, sautés and so on in no time at all so it's really convenient. Process the clams like this when they're on sale, to save money and enjoy more delicious meals too. During the hot summer months, do this in a cool location in a short amount of time.