Heat the oven to 170°C (325°F) gas 3.

in a bowl, combine the flour, chilli powder, very finely chopped garlic and a good pinch of salt.

Cut the pork into 25 mm (1 in) cubes, discarding any excess fat or gristle. Add the pork to the spiced flour and toss to coat well.

Heat 25 g (1 oz) butter and the olive oil in a flameproof casserole. When foaming subsides, add enough pork cubes to cover the base of the casserole and brown thoroughly on all sides over a steady, moderate heat. Remove the browned pork to a plate and brown the remaining pork. When all the meat is browned, return it to the casserole.

Cover the pork with the chopped tomatoes and season with more salt if necessary. Cover the casserole and bake for about 1 1/2 hours in the oven.

When the pork is tender, melt the remaining butter in a small frying-pan and saute the pine nuts until golden.

Add the soured cream and the sliced celery to the pork. Heat gently, stirring, until well mixed. Add the pine nuts, correct the seasoning and serve immediately.