Pat tenderloins dry with a paper towel. The more dry the outside of the meat is, the better crust you'll get while cooking.
30 minutes before cooking, season the steaks liberally with salt and pepper. Let the tenderloins sit at room temperature for 30 minutes before cooking.
Heat cast iron skillet over medium-high heat. Add lard and swirl to coat the pan.
Place tenderloins in the hot cast iron pan. Cook for 2-3 minutes per side or until internal temperature reaches 120-125°F for medium-rare. Tenderloins usually have 3(ish) sides. Don't forget to sear the third side!
After searing the 3 major sides, you can do a quick 10-15 second sear on any small sides that look raw on the outside.
Cooking time will vary depending on the size of your tenderloins and the temperature of your pan.
Remove tenderloins to a cutting board and let rest for 10 minutes.
Slice or cut into medallions (about 1-1 ½" thick).
Sprinkle with flaked sea salt, if desired. Serve and enjoy!
Notes
If your tenderloins are on the larger side, preheat your oven to 375 degrees. If the internal temperature of your steaks is low but the outsides are done, put the pan in the oven for a few minutes to finish the steak. Check the temperature frequently so they don't overcook!
Season the steaks just before cooking. Once you put salt on the steak, it immediately starts drawing the moisture out so it's best to wait as close to cooking as possible to add salt.