Wash potatoes and cut them into thin slices.
Place potato slices in a large bowl and add olive oil, salt, pepper and paprika. Stir to coat potatoes.
Lay out potato slices in a single layer on a cookie sheet lined with either a silpat liner or a sheet of parchment paper.
Use a basting brush to coat the potato slices with any remaining seasoned oil left in the bowl.
Bake potato slices at 450° for 20 minutes.
While the potatoes are in the oven preheat a cast iron skillet on the stove. You want a really hot skillet so you get a nice char on the steak.
Season sirloin steak liberally on both sides with salt and pepper.
Cook steak over medium high heat to medium rare doneness. About 4-5 minutes per side. The lenght of time will depend on the thickness of the steak you are using; adjust cook time accordingly.
Remove skillet from heat. Remove steak from the pan and allow steak to rest for 10 minutes.
Using a paper towel, carefully soak up any excess oil in the cast iron skillet.
Slice steak into ½ inch chunks.
When potatoes are done, transfer them from the cookie sheet into the cast iron pan, laying them out in a spiral pattern to cover the bottom of the skillet with a layer of potato slices.
Top the potato slices with the cubed steak.
Layer on the Pepper Jack and Cheddar cheeses.
Place skillet in the oven and set the temperature to broil. Broil until heated through, cheese completely melts and starts to brown along the edges.
Serve topped with a dollop of sour cream, a sprinkle of green onions and salsa if desired.