Directions

1. Using a small food processor, grind the koji into a fine powder and sprinkle liberally over the steaks.
2. Place the steaks on a rack over a baking sheet, cover with foil, and refrigerate for 48 hours.
3. After 48 hours, rinse the steak and brush lightly (with a clean brush) to remove the koji. Pat the steaks dry.
4. Place 2 sprigs rosemary, 2 sprigs thyme, and 2 cloves garlic on each steak and carefully slide each into a sous vide bag. Vacuum seal the bags.
5. Place in the sous vide machine and cook at around 130°F for 2 1/2 hours.
6. When the steaks are done, remove from the bags and season liberally with salt and pepper.
7. Finish the steaks on a hot grill for a few minutes on each side.
8. Top each steak with a couple of pads of compound butter.
9. To make the compound butter, place the softened butter on a large sheet of plastic wrap.
10. Finely chop the shallot, garlic, rosemary, and thyme and sprinkle all over the butter.
11. Roll the butter up tightly in the plastic wrap and refrigerate until firm.