Roast Beef (Top Sirloin Roast) (I don't eat beef much so this info has been pulled from other sources and not from experience so use at your own risk).

There are two different ways of doing this.

Step A (I like this step because it is less effort)

Preheat oven to 325°F and then cook for 25 to 30 minutes per pound (might be about 40 minutes per pound but seems to take about 2 hours for 2.2lb roast)
Season beef with herbs and spices or a rub.
Place roast, fat side up, on a rack in a shallow roasting pan.
Insert a meat thermometer into thickest part of roast, in center, not touching bone or fat.
Do not add water, do not cover.
Roast meat to 5 to 10 degrees below desired doneness. Temperature will continue to rise to desired doneness.
Let roast stand 15 to 20 minutes before slicing or serving. It will be easier to carve and the juices will set up.
Attempting to carve your roast without allowing it to rest will cause significant loss of juices.

Beef Roast Doneness:

Roast to desired doneness by removing roast from oven when an oven dial or instant-read meat thermometer inserted in the center of the thickest part of roast reads 5 to 10°F below final doneness temperature.
Doneness - temperature to remove it from oven at / final cooking temperature
Med-Rare - 135°F / 145°F
Medium - 150°F / 160°F
Well Done - 160°F / 170°F

Step B

Oven-sear, roast and let stand

Oven-sear by placing roast in preheated 450°F oven for 10 minutes.
Reduce heat to 275°F. Cook to desired doneness, removing from oven when 5°F below finished temperature. (Prime Rib with bone will take an extra 30 to 45 minutes. Tenderloin will take 30 to 60 minutes less.)
Cover and let stand for at least 15 minutes. Roasts can stand 20 to 30 minutes before carving into thin slices.

1kg - 2 to 2.5h, 1.5kg - 2.25 to 2.75h, 2kg - 2.5 to 3h, 2.5kg - 2.75 to 3.25h.