Heat a large cast iron or non stick skillet over high heat. Add 1 tbsp. butter and the thinly sliced onions. Cook till soft and golden brown. Add the Balsamic Vinegar and cook just till it evaporates. Remove the onions from the skillet.

Butter the cut sides of the buns and toast lightly in the skillet over medium high heat. Remove them to a plate.

Turn heat to high again and add 1 tablespoon each of butter and olive oil. When the butter is sizzling, add the beef slices a few at a time. Flip them over after about 1 minutes or when brown. As the second side begins to brown, push them to the side of the pan and continue adding more beef till all of it is browned.

Immediately turn off the heat. Top the beef in the pan with the grated cheddar cheese and allow it to sit while you spread the buns with sauce.

Scoop about 4 ounces of meat and cheese onto each bun, then top with Jalapeno Ranch Sauce, then the top of the buns.