I was recently introduced to the tri-tip cut of beef, it has to be one of the juiciest and tender pieces of meat! I get mine from a local butcher, it tastes much better than the meat I get at the grocery store. This cut has a large fat cap on it, I smoke my roast without removing the fat cap and place it so the fat cap is at the top so it drips over the meat while it cooks. I use a Masterbuilt 40" electric smoker. With quite a bit of experimentation I came to the conclusion that less is more when it comes to seasoning this cut. I keep it simple, using a dry rub of kosher salt, ground pepper, garlic powder, and a TOUCH of cayenne. The best temperature I found is 230°F, it cooks perfectly and stays juicy. The last time I made one, last week, I used hickory AND mesquite which gave it a delicious flavor. I cooked mine to an internal temperature of 138°F and finished over the fire on my grill to medium rare, searing the meat and concentrating on cooking the fat cap. It was absolutely superb!! I served it with a tossed salad, garlic cheese mashed potatoes, and sweet white corn.
