Give spinach a good dunk. Particularly gritty leaves may need a couple of changes of water to be thoroughly cleaned.
Mature spinach with thicker, less tender leaves is the best candidate for cooking, where its mineral quality can be tamed with cream, butter, or cheese. Blanching removes bitterness from older spinach, and it makes further cooking simpler and faster. A testament to its versatility, spinach works with sharp and tangy flavors, like mustard and lemon juice, as well as with creamy, eggy components. Some people report a dry, chalky sensation on the teeth and on the roof of the mouth when eating spinach. Agricultural scientists say that this comes from the leaves' high concentration of oxalic acid.
Because of the increasing availability of pre-washed leaf-picked spinach, with tender, edible stems, you can cut spinach preparation time to a bare minimum. But don't stint on washing. Spinach grows in sandy soil, and the tiniest bit of grit can ruin its delicious pleasure.
For every cup of cooked spinach, you'll need to buy about a pound of fresh.