1. Tenderize the steak and season both sides with some steak spice. Then wait for about 15 minutes, allowing the steak to rest.
2. Go ahead to preheat the grill – medium heat.
3. Then grill for 5 minutes over high heat now. Turn the steak and cook for another 5 minutes, or until your desired doneness has been achieved.
4. You can then place the steak on a cutting board – a serving tray works too – after removing it from the grill. Now place a piece of aluminum foil loosely over the steak.
5. Leave it to rest for 5 minutes.

Watch this video link to get a visual direction of how to cook sirloin steak on a grill.