Onion Gravy

This gravy is delicious with sausages and mashed potato.  You can make it in advance and when cool, if you put a layer of cling film over the top it will be fine for a couple of days in the refrigerator.

1. Melt the butter in a saucepan and add the sliced onions.  Stir them around and cook over a gently heat for about 5 minutes or until they are soft, translucent and just starting to colour at the edges.
   
2. Sprinkle over the flour and mustard powder (if using) and give the pot a good stir.  Let the onions cook for a further minute over a gentle heat.
3. Whilst stirring, add the worcestershire sauce (if using) and gently add the stock a little at time up to about 300ml – you may not need to use all of it – to get to a nice thick consistency.  Let the sauce come up to the boil and, stirring occasionally, let it cook for a further 5 minutes.  If you want a slightly thinner sauce you can add a little of the remaining stock.