Bring a large saucepan of lightly salted water to the boil. Add the onions and simmer for 20
minutes or until tender. Drain and set aside until cool enough to handle.
Thickly slice the onions and place in a shallow dish. Sprinkle the parsley and olives over and
season to taste with pepper.
Whisk the vinegars and olive oil together in a bowl, then whisk in enough of the water to make a
Pour the dressing over the onions and olives and serve at room temperature.