Ingredients:
Simply mix ingredients well to make rub.
Take the tri-tip out of the fridge and let it come up to room temperature for fifteen minutes. Pick a well marbled tri-tip. If you get an untrimmed one, you should trim some of the excess fat off before cooking, but leave the fat cap on one side as this will help keep it moist and turn into a wonderful gravy in the end. This will give it some time to breathe and help the rub stick to the meat. I also don't like putting an ice cold slab of meat on the hot grill, I prefer to let the meat warm up a bit first.
Rub the rub all over the tri-tip. You can add a little olive oil to the tri-tip to help the rub stick, but I usually find that it isn't needed. I usually just throw the rub and tri-tip in a freezer bag and shake.
Cook as desired (BBQ or oven). BBQ method will follow.
Method:
This is my standard method for cooking tri-tips on regular BBQ's. This can be applied to both coal and propane. This method can be used with just about any rub or marinade, it assumes that you are cooking a two to three pound tri-tip.
Fire up the grill - Heat one half of your grill as indirect heat is the best way to cook a beef roast like this. The goal is to get the BBQ hot, but to leave a space on the BBQ so that the tri-tip will not sit directly over fire. The tri-tip can start to leak and fuel the fire, so it is important not to cook the roast over direct fire.
Start cooking (char and sear), 3-5 minutes - After the BBQ is ready, put the tri-tip directly over the flame for three to five minutes with the fat side up. The goal here is to char and sear the meat without lighting it on fire. Use your best judgement when the flames start to rise. In short, just don't let it catch fire but do let the rub on the outside get a bit crispy. If you used olive oil to make the rub stick, be extra careful as the roast will be even more flammable.
More charring and searing, 2-3 more minutes - Flip the tri-tip so you can char and sear the roast with the fat side down this time. Again, stay close and keep an eye on it. You need to be sure not to set it on fire during the opening act.
One more time with the charring and searing, 2 more minutes - Flip the tri-tip so you can char and sear the roast again with the fat side up. Again, stay close and keep an eye on it. You need to be sure not to set it on fire, you just want that fat side to get ready to melt.
Cook over indirect heat, 20-30 minutes (covered) - Flip the tri-tip over after the three searing sessions (it will now be fat side down) and move it to the part of the grill that does not have fire under it (indirect heat). Cover your grill, but don't close the vents all the way because you still want the fire to breathe. If you have some wood chips for smoke, this is the time to add them. I usually close the vents about 80%. You should be able to let it go for about 20 minutes now.
Flip it over indirect heat, 20-30 more minutes (covered) - Flip the tri-tip over after the right amount of time (depending upon how well done you want the meat). This will leave the fat side up. If you can cover your grill, if you can. The goal here is to finish cooking the roast with the fat side on top. As the roast comes up to temperature, hopefully the fat will melt as much as possible and seep into the meat. Beef is done (rare) when it has an internal temperature of 145 degrees. (160 degrees for medium and 170 degrees for well done). Feel free to use your favorite meat doneness test to figure out the flip point and when to take the roast off the grill (next step).
Note - I've use a thermometer in the past, but honestly I have cooked these so many times at this point in my life that I don't probe them anymore. I would recommend that you use one for the first couple times you cook this so that you get a feel for when it is ready to take off the grill, after a while you will be able to tell when it is ready based on the touch test. Remember, the tri-tip will continue to cook (internal temperature will raise) for ten minutes after you take it off the grill. You can safely assume that the meat will climb five more degrees after removing it from the grill. In some cases, it has gone up ten degrees after taking if off the fire.
Remove the meat from the grill and wrap in foil, about 10-15 minutes - Carefully wrap the tri-tip in foil. The goal here is to be able to catch all of the juice from the tri-tip in the foil as it finishes cooking. You can pour this over the meat after slicing or serving. I keep the fat side up and slide a large piece of foil under the roast. Using my BBQ gloves (heat resistant), I can carefully wrap the roast up. It is important not to have any foil seams on the bottom as the juice will leak out. At this point, I usually let the meat rest in my over or microwave for fifteen minutes. This step is very important. If I were to take the tri-tip off the grill and just slice it, juice would run out all over the cutting board, not to mention that the meat is still cooking. It is crucial to give it some time after taking it off the BBQ.
Remove from foil but save the juice, slice against the grain and serve - Basically just get the tri-tip out of the foil and onto a large cutting board. Keep the juice in the foil so you can serve it with the meat. Slice the tri-tip against the grain. I found this video on YouTube that really explains how to carve a tri-tip perfectly. This is definitely worth the watch and it is under three minutes: https://youtu.be/gmxHmuV4vTU