Soak the clams in cold water for 5 minutes, drain, refill with fresh cold water, and scrub each clam with a very stiff brush. Repeat several times until no sand settles, and discard any clams that do not clamp shut when touched.
In a broad pot, heat the olive oil over medium. Cook the chopped shallots or onion until translucent, add the garlic and cook until it turns a pale gold, then stir in the parsley.
Add the wine with the dissolved cornstarch and the chopped chili pepper. Cook at lively heat for about 2 minutes, stirring often, then add the clams.
Cover and keep the heat high. Check frequently and move the clams around, transferring opened clams to a serving bowl as they open.
Turn off the heat. Tilt the pot and ladle the juices over the clams, taking care not to disturb any sand at the bottom. Serve at once with grilled bread.
