Prepare the onions: peel and plunge them into boiling salted water. Cook for 15 minutes, until the outer leaves are soft but still slightly crunchy. Refresh in cold water, drain and leave to cool. When the onions are cool, cut them in half across the middle. Pull out the centres to make eight cups with the four outer leaves, reserving the other removed leaves. If you are left with a hole in the base, place another leaf in the bottom to seal it.
Heat a spoonful of oil in a sauté pan. Chop the onion leaves removed from the centres and sauté them in the oil for a few minutes, taking care not to brown them. Add the bread, stir and continue to sauté for a couple of minutes before stirring in the tuna mixture.
Spoon this mixture into the onion cups, filling to just above the rim. Sprinkle with breadcrumbs, drizzle a little more oil over the tops of the onions and carefully pour
© 1993 Alastair Little. All rights reserved.