Please help me cook this steak!

[baffledmummy]

I've a lovely piece of steak - about 1.5 inches thick. My DM used to make steak for us cooked with some stock, onions and wrapped in foiled and cooked in the oven. It used to be that lovely melt in the mouth steak that falls apart...mmmm... Anyway...I bought the steak, but then realised I have no idea a) how much stock to use b) what temp should be cooked at or c) how long to cook it for!!!
Anyone help?

BBC Food - Braised Steak with Gravy

This looks close to what you want.

You need the right kind of steak though. What cut do you have op?

Thanks for the link!
I've got sirloin - think i'm going to go for an hour at 180c - fingers crossed!