The first thing you need to do is place the cast iron skillet over medium heat and add the oil to it.

Second, add the chopped potatoes and onion slices to the cast iron skillet and arrange them in an even layer.

Third, sprinkle the salt and pepper over the potatoes and onions.

Next, allow the potatoes and onions to cook and develop a crust on the bottom before stirring them around.

Once you have stirred the potatoes, arrange them in an even layer, cover the skillet with a lid, and let the part of the potatoes and onions that is sitting on the bottom of the pot/skillet develop a crust. (If the potatoes are drying out, add enough water to create steam before placing the lid back on the skillet.)

Then, stir the potatoes and onions again and arrange in another even layer in the cast iron skillet.

Keep doing this until most potatoes and onions have developed color and crisp and are cooked through.

Next, add your leftover pot roast or deer steak meat to the potatoes, onions, and gravy.

Once the meat is warmed through, remove it from the heat.

Finally, serve immediately with your favorite sides. Don't forget the ketchup!