1 Scrub clams and let soak for 1 hour in cold water, chaning the water once. (If using frozen clams, let thaw first.)
2 Meanwhile, peel onion and garlic and finely chop both. Halve chile lengthwise, remove the seeds, rinse and pat dry. Cut chile into thin strips.
3 Rinse parsley, shake dry, pluck leaves and chop coarsely. Squeeze juice from lemon.
4 Drain clams in a sieve. Discard any that remain opened.
5 Heat oil in a large pot over medium heat. Cook onion and garlic until translucent, about 2 minutes. Add chile and sauté until softened, about 1 minute.
6 Add wine and bring to a boil.
7 Add clams, cover and cook over high heat until all the clams have opened, about 4 minutes, shaking pot a few times.
8 With a skimmer, transfer clams to a plate. Remove any clams that have not opened.
9 Add parsley to the cooking broth and season with salt, pepper and lemon juice.
10 Pour broth over the clams and serve hot or warm.