Calves' liver with pancetta

Balsamic vinegar that has been aged in wooden casks for 15 years or more is very different from the mass-produced balsamic, which is astringent and watery. The vintage vinegar is thick and syrupy, with a rich, complex flavour.

Serves two

4 thin slices pancetta, rind removed

2 slices calves' liver, each about 225 grams and about 1cm thick

15 grams unsalted butter

1 large onion, sliced about 3mm thick 1 large red chilli, sliced

A few thyme leaves

15ml aged balsamic vinegar

Fine sea salt and freshly ground black pepper to taste

Cooking oil, as required

- Pour cooking oil to a depth of 5mm in a skillet set over a medium flame. When the oil is hot, add the pancetta and fry until crisp; cook the slices in batches, if necessary.

- Drain on paper towels and pour off most of the oil.

- Sprinkle salt over both sides of the calves' liver.Heat the skillet (the one used to cook the pancetta) until it's very hot.

- Add the calves' liver and sear on both sides until well browned.

- Lower the heat then continue to cook the calves' liver until done - the meat should be slightly pink inside. Don't overcook or the liver will be tough.

- While the liver is cooking, heat the butter with about 5ml of cooking oil in another skillet.

- Add the onion, chilli and thyme leaves then sprinkle lightly with salt. Stir frequently over a medium-high flame until the onion is tender.

- Remove from heat and stir in aged balsamic and freshly ground pepper.

- Sprinkle the calves' liver with pepper then put a slice on two plates.

- Add two slices of pancetta to each portion, then spoon the onions on top.

- Serve with mashed potatoes.