Preheat the oven to 150 degrees.
Gradually add the Guinness, stirring as it thickens. Nestle the Bouquet Garni into the middle of the juices and bring to the boil.
If you find that too much of the liquid has evaporated or the sauce is a little no the thick side, add some more Guinness of if you have none left then a glug or two of red wine.
Serve hot with mashed or new potatoes or crusty bread.