There are many ways to cook a steak, but what I prefer is to pan-sear the steak first, then wrap it in alumnium foil and roast it in oven at 400 degrees for about 40 minutes, or depending on how you want it done. Prepare the sauce in a pan, then pour over half the sauce on the steak, half on the side when serving.
The success of a steak depends on how fresh the meat is. The rule of thumb is: when you select a piece of steak, lightly press it down with your fingers, if it bounces right back, it means that the steak is fresh, otherwise it's not so.