In a small bowl, combine the dry rub seasonings. Generously season the tri tip and coat on all sides with the spice mixture.
Place the tri tip directly on the grates of your smoker. Cook for 60-90 minutes, until it’s 5-10 degrees below your desired final temperature, as shown below.
Once the tri tip is finished smoking, preheat a large cast iron over high heat on your stove.
Add the butter and oil. Once melted, add the tri tip to the skillet. Sear for 2-3 minutes per side, until well browned.
Place the tri tip on a cutting board and allow to rest for 15 minutes. Slice against the grain, rotating as needed, since the grain changes throughout.