Shirley's Perfect Rare Roast Beef

Preheat oven to 500 degrees. Wait for a few minutes before you put your roast in, so it gets as hot as possible.
Put the roast in a shallow pan. (I use a cookie sheet).
Cut onion into thin rings, and put all over the top and sides of the roast using toothpicks if necessary. I sit a few slices on the bottom of my roast too.
Sprinkle roast generously with garlic powder, or to your liking. DO NOT SALT roast, or you will dry it out.
Put roast in the oven on the middle rack.
Bake at 500 degrees for 5 minutes per pound, then shut off oven, and let sit in the oven for 1 hour. DO NOT under any circumstances open the oven door! VERY IMPORTANT!
After you turn off the oven and your roast has baked for l hour, take it out of the oven, and let sit for 15 minutes, to allow juices to distribute in the roast.
I use my electric knife to cut my roast, and place on a serving dish.
Don't forget to make the gravy!