This one I did fajita style in cast iron but when I do it on the grill like a steak and top rack it fat side up til it hits medium doneness. I'm usually a medium rare kinda guy but with tri tip I prefer medium. Most places around here trim the hell out of it til theres virtually no fat but I prefer untrimmed cuz when you top rack it all those juices go down into the meat it comes out amazing.
Edit: the ones they sell here are thick logs of meat and take a while to heat through. If the ones you saw are thinner then yea, just cook it like a steak
Let's be honest here, I was not even remotely sober when I decided to do this. Local shop had steak on special, so ate the first half 4 days ago, now for the second 2 pieces which has been marinating in olive oil for 4 days.
My pepper grinder decided to blow up like a dickhead while seasoning my peas, sending shit all over my stove, floor, etc, but vacuuming day is not for another 2 weeks, coz my vaccum cleanier is a pain in the ass crock of shit. The lil bastard pepper thing is ashamed and has decided to hide in this pic.