The night before you want to cook your beef tenderloin, season liberally, wrap in plastic wrap, place on a large plate to catch any juices, and store in the refrigerator.
About an hour before you want to cook, take the beef tenderloin out of the refrigerator to take some of the chill off.
Place charcoal in the bottom of your smoker.
Soak your wood chunks in a large bowl filled with water for 30 minutes. Drain the wood chunks and arrange them on top of the charcoal in the bottom of your smoker.
Target your smoker temperature to 225-250 degrees. Maintain that temperature for 15-20 minutes before placing the meat in the smoker.
Once you have placed the meat on the cooking grate in the smoker, close the lid and cook to an internal temperature of 120-125 degrees for rare and 130-135 degrees for medium rare. You can expect this to take approximately an hour to an hour and a half, depending on how many pounds of meat you are cooking.
Once the beef tenderloin has reached the temperature of your choosing, remove it from the smoker and wrap in aluminum foil.
Allow it to rest for about 25-30 minutes to let the juices settle back into the meat before slicing.
Arrange a bed of kale or arugula on a serving platter. Place the beef tenderloin on top of the greens and cut into 1 1/2 inch slices with a serrated knife. Garnish with parsley.