Put your steak in the smoker set at 180-225 degrees and let it smoke until the internal temperature is 100-110 degrees. If you're working with a thicker cut of meat - 2" plus in thickness - you'll want to take the internal temperature up to 125 degrees.
When your steak gets to the target internal temperature, pull it off the grill and tent it with foil, and turn up the temperature of your smoker to 500+. If you have a cast iron skillet, put it in the smoker while it's warming up.
Right before you put your steak in the skillet, add a tablespoon of butter.
Once the smoker is at 500+, put your steak back in. After 1-2 minutes flip the steak, and let it cook for an additional 1-2 minutes.
Let your steak rest for at least 10 minutes. If its a thicker cut of meat you can let it rest for up to 20 minutes.
Notes
If your smoker doesn't get up to 500+ I'd recommend searing the steaks in a cast iron skillet on your stove. Turn on your hood vent and crack a window so the smoke alarm doesn't go off.