Transfer to the grill and cook for about 5 minutes, then turn one-quarter turn and cook another 5 minutes. (Turning will give you those nice grill marks.)
Flip the tri-tip and repeat the process.
Check for desired doneness by using the finger-to-thumb method. (Watch the video for this technique.)
Remove from the grill and let rest for 5-10 minutes.
Slice the tri-tip against the grain and serve with your favorite sides!