How to make a red wine sauce
Equipment you will need for this technique
Chopping board, knife, two sauté pans and a sieve.
Slice half an onion and brown the slices in a large sauté pan, leave them for 4-5 minutes until the bottom side is blackened. Then add the red wine and cook on a high heat to evaporate the alcohol. Add the balsamic vinegar followed by the beef stock. Leave it on a rapid boil until the volume of liquid has reduced by about 75%, this should take about 10 minutes.
Pass it through a sieve into a clean pan and add a pinch of sugar to offset the bitterness. Then add a knob of butter, this will thicken the sauce and give it a lovely shine.