Heat 50 g (2 oz) of butter in a pan. Add 100 g (3½ oz) finely sliced onion and 50 g (2 oz) finely sliced shallot and cook to a golden colour. Moisten with 4 dl (14 fl oz or 1¾ U.S. cups) white wine, reduce by half and add 4 dl (14 fl oz or 1¾ U.S. cups) Sauce Demi-glace, 2 tbs tomato purée, 2 dl (7 fl oz or ⅞ U.S. cup) white stock, 80 g (3 oz) raw lean ham, 1 small clove of crushed garlic and 1 Bouquet garni. Bring to the boil and simmer gently for 25–30 minutes.
Remove the ham and keep on one side and pass the sauce through a fine sieve.
Reheat the sauce and finish by adding the ham cut in very small dice, a little grated horseradish and a good pinch of chopped parsley.
This sauce is specially suitable for serving with grilled or spit-roasted red meats.