I sear at high temp and then raise the grill up above the coals to
complete the cooking more slowly. I certainly wouldn't want to
argue with the Santa Maria site but I do usually take the fat off.
Sometimes I cook a tri-tip in a different, non-Santa Maria style.
I remove the fat and save it in a single piece. Marinate the meat
in a teriyake-type sauce (Soy sauce, garlic, brown sugar, rosemary,
mustard, wine, & wine vinegar). Sear both sides, then cook more
slowly. Add catsup, A-1 sauce, and Worcestershire sauce to the
marinade to create a thicker basting sauce. Soak the fat in the
basting sauce and lay it over the top side of the meat as it cooks.
When you turn the meat, take the fat off, swish it around in the
basting sauce, and then lay it on top of the cooking meat again.
Seems to work pretty well. But I don't like to do it when the
Santa Maria purists are watching.