Preheat your smoker to 250 F
Mix the smoked salt, garlic powder, onion powder, and black pepper in a dish until well combined. Rub this mixture onto all sides of the top sirloin roast
Heat the olive oil in a skillet until it starts to shimmer; use medium heat. Sear the seasoned roast for 3 minutes on each side, and cook for longer until browned on all sides
Wrap the seared roast in aluminum foil and seal it tightly and place it into the preheated smoker
Add your soaked wood chips to the smoker around the roast and let it smoke for 45 minutes or until the internal temperature is 145 F. This can take around 4 hours, depending on your smoker's temperature
Once cooked, remove from the smoker and loosen the aluminum foil for 10-15 minutes. Cut into the preferred size of slices and serve