Pre-heat your oven to 400 degrees F.
In a small bowl, mix together paprika, brown sugar, onion powder, oregano, ground mustard, Kosher salt, cumin and olive oil.
Rub the spice mixture into the pork and marinade for about 30 minutes (or up to 8 hours).
When you're ready to cook the pork, heat 1.5 tablespoon of butter in a cast iron skillet over medium heat.
Once the pan is hot, cook the pork for 2 minutes on one side.
Then flip and cook 2 minutes on the other side.
Turn off the burner and spoon some of the melted butter overtop of the pork. Then carefully place the whole skillet into the oven for about 4 minutes or until internal temperature reaches 150 degrees F. Larger pieces of pork will take longer to cook.
Remove the pork from the skillet and let rest for 5 minutes before serving.
As the pork rests, it'll come up in temperature to 165 degrees F.