To purge the clams, place them in a large bowl. Cover with plenty of cold water and stir in a tablespoon of sea salt. Soak for 1 hour, changing the water a couple of times. Drain and rinse the clams well.
Meanwhile, thinly slice the garlic cloves, slice the chilli if using, and finely chop the parsley.
Heat the olive oil in a large frying pan over medium heat.
Add the garlic and chilli and gently fry for 1–2 minutes, or until the garlic begins to turn golden. Take care not to burn it.
Increase the heat to medium-high. Add the drained clams and stir for about 1 minute.
Pour in the white wine, cover the pan with a lid, and steam for 2–3 minutes, or until all the clams have opened.
Remove the pan from the heat and discard any clams that remain closed.
Stir in the chopped parsley and season with salt to taste.
Serve immediately with crusty bread for dipping, while still hot.