My beef sirloin was medium rare as I asked and the cut was perfect.
So when the edges change from red to brown, the middle is moving from rare to medium-rare to rare.
A good rule of thumb is to allow 12-15 minutes per pound for a rare roast and 15-18 minutes for a medium rare roast.
The roast is done when the meat thermometer reads 115 to 120 degrees for rare or 125 to 130 degrees for medium rare.
Filet mignon is best when served rare or medium rare.