Peel the onions, leaving them whole. Cover with fresh cold water and bring to the boil. Simmer for 5 minutes to blanch and then drain. Return the onions to the pan and add the remaining ingredients except the parsley. Bring up to the boil, then cover and simmer gently for 25 minutes or until the onions are tender.
Using a perforated spoon lift out the onions and place in a serving dish.