- Pat the flank steak dry on both sides using paper towel. Spoon the shio koji over the surface, covering well, then place into a ziptop bag and seal. Place the bag into the refrigerator to marinate for 4-6 hours or overnight.
- Spread the sushi rice out on a tray lined with parchment paper to allow the grains to dry out as much as possible. Ideally, it will sit for at least 30 minutes to dry.
- Pre-heat a grill to high heat, about 20-30 minutes before you’re ready to cook the steak.
- To prepare the crispy rice, you will work in batches. Add half the oil and half the cream to a nonstick skillet over medium high heat. Whisk to combine. When hot, add half the rice, pressing down gently with a large spoon to form a large flat disc that covers the entire base of the pan. Season with salt. Lower the heat to medium and cook 10-15 minutes until the grains begin to color and become crisp on the bottom. Remove to a large bowl and repeat with the remaining oil, cream and rice.
- Add the Furikake to the bowl and toss to combine with the crispy rice.
- Combine butter and miso paste in a small bowl, and mix well with a spatula to combine, then set aside.
- Scrape the excess koji from the steak then place onto the oiled grill. Cook the steak, turning every 3 minutes, until a nice color has developed and it reaches an internal temperature of 130-135 degrees on a meat thermometer. Remove steak to a board and cover with foil, allow to rest 10 minutes.
- To serve – spoon crispy rice into the bottom of a shallow bowl. Slice steak (after resting) and nestle several slices on top of rice. Top with a generous amount of miso butter and a sprinkle of chopped scallions.