Heat the oven to 170°C (325°F) gas3.

Pat the pork dry with absorbent paper and season to taste with salt and freshly ground black pepper. in a large flameproof casserole, heat the butter and olive oil. When the foaming subsides, brown the pork evenly on all sides. Remove from the pan.

Add the chopped onions to the fat remaining in the pan and cook, stirring occasionally with a wooden spoon, for 20 minutes or until golden brown.

Pour off the excess fat and stir in the paprika, dry white wine and chicken stock. Season with caraway seeds and salt and pepper to taste and bring to the boil, stirring occasionally with a wooden spoon.

Return the browned pork to the casserole. Cover and cook in the oven for 2 hours, or until tender.

Remove the pork from the casserole, reserving the sauce, and place it on a heated serving dish. Remove the string and keep warm.

Strain the sauce into a small saucepan and bring to the boil over a high heat. Boil rapidly for 3-4 minutes, or until the liquid has reduced by about a quarter.

Stir in the beurre manie, a piece at a time, and continue to boil, stirring constantly, until the sauce has thickened.

Stir in the soured cream and finely snipped chives. Warm through gently without boiling. Correct the seasoning and pour the sauce into a heated sauce-boat. Garnish the pork with chives and parsley. Serve immediately, accompanied by the sauce.