I’m not sure how you feel about this, but I think tri-tip of beef (or triangle roast in some parts of the country) isn’t what it’s cracked up to be. It’s tough, not all that flavorful and nearly always has to be marinated and roasted or grilled to a cinder to be any good.
Some people do salivate when they hear “tri-tip” spoken of as something they are likely to eat at a party, but when they get the beef, they are disappointed. It is a good example of the old rule of thumb: Something that smells good cooking may not always taste good.
Tri-tip in previous times was used almost exclusively as hamburger meat, and it worked well for that. But butchers (and who can blame them) saw tri-tip as a way to get more money from customers by selling a cut of meat that masquerades as a quality roast.
People took these slabs home, put a little salt on them, placed them in the oven and waited the recommended cooking time. When they took it out of the oven and cut it up though, it turned out to be just a step above shoe leather.
Then along came marinades, dry rubs, chemical tenderizers — you name it. This time, the backyard grill was considered the ideal cooking spot, and the tri-tip roasts that came off those grills largely were charred black. Slicing them revealed either seriously overdone meat or beef done like charcoal on the outside and nearly raw inside. In either case, it was usually too tough to chew without a lot of effort, and largely without quality beef flavor.
You can, of course, cook the meat slowly, wrapped tightly in foil, then finish it on the grill. The slow cooking tenderizes it, the grill gives it a bit of flavor.
Some professional local cooks, such as the Petruccis, seem to be able to turn tri-tip into flavorful and tender dining, but for the do-it-yourselfer, like yours truly, it requires too much patience and skill.