In California we do it Santa Maria style. You can use Suzy q prepared rub or just simply season the tri tip as you would a steak. Generous sea salt or kosher salt, fresh ground black pepper, granulated garlic and some dry parsley. Let it sit on the counter while you get the fire ready for a reverse sear. Indirect cooking until 120 than on direct until its nice and seared. Temp should be around 135 or so for a nice medium as the temp will rise a little bit when rested. Slice against the grain and serve.
I will actually be doing tri tip tomorrow.
Q-ING on my: PBC, Weber OTG & Cookshack Smokette - Temped by Thermoworks TW-8060