Heat the oil in two medium skillets over medium-high heat. Add the butter and melt.
Add the onion to one skillet. Stir and saute until softened and golden in color.
Meanwhile, add the mushrooms to the other skillet. Stir and saute until the mushrooms are softened.
Remove onions and mushrooms from heat.
Cook your hot dogs as desired. Toast the buns if desired.
Place dogs in buns. Top with onion, mushrooms, cheese and crumbled bacon.