Shio Koji-Marinated Pork Shoulder Steaks

In a very large resealable plastic bag, coat the pork steaks with the shio koji. Seal the bag, pressing out the air. Set the bag in a baking dish and refrigerate overnight. Let the pork stand at room temperature for 30 minutes before cooking.

Remove the pork from the marinade; scrape off any excess. Season the pork with salt. In a cast-iron skillet, heat the oil until shimmering. Add the pork steaks and cook over moderately high heat, turning once, until lightly charred, 2 minutes per side. Cover the skillet and cook over low heat, turning once and wiping the moisture from the bottom of the lid, until an instant-read thermometer inserted in the thickest part of the steaks registers 135°, 10 minutes. Transfer the steaks to a carving board and let rest for 5 minutes. Slice the steaks across the grain and serve.