Hope this helps....

If it's a big piece of sirloin you want to cook in the oven just pour over the red wine, add very finely diced onions and cook as normal in the oven. About half an hour before then end, add sliced mushrooms to the juices and cook again.

Remove the meat and leave to rest. Put all the juices in a pan, add a splash more red wine, and reduce by about a half. Add a knob of butter and whick in, season and there you go!

OR

Fry very finely diced onions in a little butter, add the mushrooms and cook down. Add your red wine, salt and pepper and let reduce. You can also add garlic if you want it, or cream to make a luxurious sauce. Gosh me I just fry up a steak sometimes, add mushrooms, add the wine and cook until the steak is done. Love those 'shrooms....