Typically I just buy Choice Grade Tri-tips, usually in bulk and untrimmed for better pricing. But if you are buying them individually, opt for the roasts that have a good grain to them (streaks of fat) and or the ones that are “gushier” when you poke them. If they are gushy as opposed to firm to the touch, they will be more tender.
I remove most of the fat from the Tri-tip Roasts (if bought untrimmed) and I always tenderize them with a “Jaccard”, as seen at top left of photo. If you dont have one of these you can use a fork for the same purpose, but it will take a lot longer. Basically you will be piercing the roast with hundreds of fork pierce marks, on both sides. This does a great job of tenderizing the steaks, and it is absolutely necessary when prepping a tri-tip roast.
The seasoning is simple, a light sprinkling of granulated garlic, heavy kosher salt seasoning, and heavy cracked black peppercorn seasoning on both sides. We have a variable grind pepper grinder (top right in photo) which we set for the most course grind setting. I have given you approximate measurements of the seasonings, but you want your seasoned steak to look like the ones in the photo. After seasoning I set the roast(s) on the smoking chamber grate on the left side of our smoker, away from the firebox.