Place fresh borlotti beans or dried borlotti beans in a pot with plenty of cold water and bay leaf, bring to a boil and cook until tender.
Season the cooked beans with sea salt.
Drain the beans, keeping some of the liquid, and transfer them to a salad dish.
Add onions, parsley, olive oil, vinegar, black pepper, and some of the reserved liquid.
Taste and adjust seasoning before serving warm, at room temperature or cold.
