In the morning, drain them, cover with lots of fresh water, bring to the boil, then lower the heat. Sprinkle in a little lemon juice, then cover and leave to simmer until tender, about 45 minutes. After about half an hour, add a little more lemon juice (this keeps the white colour of the beans from becoming brown) and a few minutes before the end of cooking time add a little sea salt.

Drain the beans, and while still hot, pour the remainder of the lemon juice and the olive oil over them. Stir well. Leave to cool, then chill.

Chop parsley finely. Just before serving stir in the parsley into the beans and add salt and pepper to taste.