it depends on what temperature you like your steak!

if it's a thick cut it's good to sear it for a few seconds on each side on a really hot cast iron pan before you put it on the grill and cook up to your preferred temp!

if you like your steaks really rare then you can just sear it and put it on your plate but make sure that your meat was processed and handled correctly before you eat it!

really searing your steaks just gives it a nice crispy outside and seals in more of the steak's juices!