Add tenderloin over hot coals and grill for 5 minutes then flip. After another 5 minutes, put tenderloin on one of its uncooked sides, and grill for another 5 minutes then flip – 20 minutes total. Check temp – people say 145 is the good amount heat, but I find that it comes out medium rare to rare. I go for 155 – 160 and it comes out juicy and with a light pink center. Maybe my thermometer is jacked up.