Heat the oil in a heavy-based saucepan over a medium heat. Add the shallots, garlic and a pinch of salt and sweat down without colour until the shallots have softened. Pour in 700ml sparkling Shiraz, the Port and add the thyme. Cook over a medium heat and reduce by three quarters. Pass the reduction through a fine sieve. In a clean saucepan bring the veal jus to the boil and add the sparkling Shiraz reduction. The sauce will have a very deep, rich colour. Season to taste with salt and freshly ground pepper before passing the sparkling shiraz jus through a sieve lined with a double layer of muslin cloth into a clean saucepan. Add the remaining 50ml sparkling Shiraz just before serving.