Rinse to clean and cut potatoes into bite size cubes. Lay on paper towels and press down to remove excess water from skins. Dice onion and bell pepper. Slice butter into 12 pieces.
Place potatoes, bell peppers and onion into aluminum foil pan. Top with shredded Parmesan cheese, pepper, and salt. Place slices of butter around the very top.
Set smoker to smoke setting. Once the smoker starts to smoke, set temperature to 400° and place aluminum foil pan on smoker grate. Close. Cook for 1 hour or until as fork tender as you'd like.