Prep your ingredients by slicing the tomato, cutting up the ham to sandwich size, and washing and cutting the lettuce.
Add butter to your skillet Over low to medium heat and let it begin to melt. Tear the sub bun in half and place in the skillet face down. Rub the buns around to ensure they soak up the butter. Once the buns get golden brown remove them from the skillet and put them on a plate.
Cover the buns with mozzarella cheese and let it begin to melt.
Add ham to your skillet. Cook the ham over low to medium heat or until the ham has seared edges. Once done place the ham on top of the mozzarella cheese.
Next layer on the lettuce and tomato. Put a generous amount of Thousand Island on and add the top bun. Sprinkle salt on top and it is ready to serve.