Preheat the smoker to 225°F/110°C.
Season the meat with the bbq rub, place it directly on the smoker, close the lid and smoke the meat (about 30 minutes per pound). Internal temp: 115°F/46°C for rare, 125°F/52°C for medium rare, 135°F/57°C for medium, and 150°F/65°C for well done.
2-3 lb tri tip roast, ¼ cup bbq rub
About 10 degrees before you reach the desired internal temp, heat a cast iron pan over high heat and melt the butter and add the garlic and fresh herbs.
2 tablespoons unsalted butter, 2 sprigs rosemary, 2 sprigs thyme, 2 garlic cloves
Sear the meat for 2-3 minutes per side, basting with butter as you sear the roast.
Remove from the grill, and allow to rest loosely tented with foil for 15-20 minutes before uncovering and slicing against the grain.