Since hot dogs are precooked, all you need to do is heat them up. For a reduced-fat hot dog, use chicken or turkey frankfurters and do not butter the buns.
Spread each of:
      4 hot dog buns, toasted if desired
with:
      8 teaspoons butter (2 teaspoons each)
Place in a saucepan and simmer in water to cover for 5 minutes; or grill or broil until well seared, about 3 minutes each side; or slice lengthwise almost all the way through, open up to flatten, and cook in a teaspoon or two of butter until browned, about 4 minutes each side:
      4 frankfurters
Place on the prepared buns. Top with:
      3/4 cup Caramelized Onions (about 3 tablespoons each)
      1 tablespoon Dijon mustard