Ingredient !
1 cup pan juices from roast meat. half glass red wine or port. 500 millilitre (1 pint)  meat or vegetable stock.
Preparation ! Place the roasting pan on the stove top over a high heat until the meat juices begin to bubble taking care not to burn as it bubbles up quickly. Pour in the red wine at once,  and scrape all the juices from the bottom of the pan with a wooden spoon or spatula. Allow this to bubble until it is reduced to a sticky, concentrated glaze. Again, do not leave the pan unattended as the reduction happens very quickly.
Add the stock and stir thoroughly to incorporate the reduced glaze. Strain the gravy through a fine sieve into a saucepan and bring to a gentle boil and reduce by one third. Once the gravy is reduced, add the butter in tiny pieces shaking the pan gently until the all the butter is absorbed adding the ice cold butter not only adds flavour, it gives the gravy a glossy shine.  Check the resting meat to see if it has given up any more meat juices (beef and lamb often will as the meat relaxes). Add these juices to the gravy and give it another quick boil.  Keep warmed until needed then strain into a warmed sauce boat.