Reverse sear: slowly bringing the meat to temperature finishing with hot sear on the outside to seal in all those yummy juices and give get a nice outside crust too.
To achieve this, cook your roast at 225 degrees. When the internal temperature (IT) reaches 110 degrees, pull the roast and lightly tent it with foil. I don't know what type of unit you're cooking with but if you have pellet smoker, crank it up to 400 degrees. If using a MES or electric smoker, you'll have to transfer the roast to your oven preheated to 400 degrees. I would cook the roast until the IT reaches 125, pull it letting the roast rest for 10-15 minutes. The meat will continue to cook during this resting period. End IT should be somewhere around 130-135 which is medium rare.
I would also Google "reverse sear." There's a ton of info out on this cooking method. When I smoke tri-tip on my MES, I use this method and finish the tri-tip on my gasser. Oh yeah, invest in a good meat probe because you should cook by temperature and not time.
If anyone has anything else to add, please chime in.
