800g red onions, thinly sliced
2 tbsp demerara sugar
salt and freshly ground black pepper
50ml balsamic vinegar
½ bottle red wine
few sprigs of thyme, leaves stripped
Melt the butter in a large pan and add the onions and sugar. caramelise the onions over a moderate heat for 20 minutes, stirring occasionally to prevent catching. onions should now be much reduced and be taking on a nice brown colour.
Add the thyme leaves, season and cook for a further 5 minutes, stirring occasionally.
Add the red wine and cook until wine is reduced, stirring as necessary until the mixture becomes syrupy.
Add the balsamic vinegar and reduce.