All liver is at its best very fresh, tender, and young. This dish should be made with the tenderest milk-fed calf’s liver you can buy, cut as thin as possible - not more than ¼-inch slices. A good butcher will do it for you, or you can do it yourself with a very sharp knife.
Peel off the skin from around the liver and trim out any nasty-looking tubes, then cut the slices into bite-sized pieces, like scraps of paper.
Heat the olive oil in a large, heavy-bottomed frying pan until hot but not smoking. Put in the onions, mixing into the oil, then cover and cook very gently until they are soft and golden yellow, not browning. This will take 30-40 minutes.
Season the onions with a little salt. Turn the heat up and add the liver, spreading the pieces out across the pan. Cook rapidly for 1 minute on each side - that is all it takes. Give a good grinding of black pepper, transfer to a warmed dish, and serve immediately with some crisp tomato fritters.
© 1999 Jennifer Paterson and Clarissa Dickson Wright estate. All rights reserved.