Two days before cooking

• Grind up the koji rice in a coffee/spice grinder or blender until it is a medium powder, not super fine. 

• Rub the steaks all over with the koji rice powder so that all sides are covered. Be thorough.
• Place the rice-and-mold-covered steaks in the fridge, uncovered, on a rack set into a sheet pan. 

• Let the steaks age for 2 days in the fridge. 

Day of cooking

• Preheat your grill, set up for direct-heat cooking. 
• Rinse the koji from your steaks, pat them dry, and season generously with salt and pepper.

• Cook your steaks, placing them over direct heat and flipping every 45 seconds. Use a TimeStick to keep track of the time! After 4 or 5 flips, you’ll start to see a crust developing. 

• Start temping the steaks from time to time with your Thermapen ONE, looking for a pull temp of 120–125°F (49–52°C) for steaks that end up at medium rare—130–135°F (54–57°C). 

• When the steaks reach your target pull temp, remove them from the grill and allow them to rest for about 5 minutes before eating. 
• Serve the steaks, and skip the steak sauce!