Soak the prunes overnight in the red wine.

Heat the oven to 170°C (375°F) gas 3. Cook the prunes, covered, in their soaking liquid in the oven for 1 hour. Remove from the oven and reserve, keeping the prunes warm.

Meanwhile, cut the loin of pork into noisettes approximately 25 mm (1 in) thick. Season with pepper, bring to room temperature, then season with salt and more pepper.

in a large frying-pan heat half of the butter and the olive oil and saute the noisettes for 7 minutes or until well done, turning them once. Remove from the pan and keep them warm. Pour off any excess fat from the pan and add 30 ml (2 tbsp) of the prune cooking liquid. Over a high heat, deglaze by stirring vigorously with a wooden spoon to remove any sediment from the base of the pan. Reserve.

While the noisettes are cooking, melt the remaining butter in a saucepan and cook the finely chopped onions, stirring occasionally, for 3—4 minutes or until transparent.

Blend the onions to a puree with 6 of the cooked prunes and 60 - 90 ml (4 - 6 tbsp) of the prune cooking liquid. Return to the saucepan and add the deglazing liquid and the remainder of the prune cooking liquid. Bring to the boil, then boil rapidly for 3—5 minutes, or until the liquid is reduced to about half its original quantity.

Arrange the pork noisettes and prunes on a heated serving dish. Pour the sauce over the pork, garnish with watercress sprigs and serve at once.