My husband loves to grill and, unless there's a downpour, he will go out there and barbeque. So this past January when it was actually snowing in Seattle, he was still determined to fire up the Weber. This is really more of a wet rub than a marinade, and it came out of the fact that I wanted to experiment with some yuzu kosho, a citrus pepper paste, that I had brought back from Japan. It turned out great and is now in our regular rotation. This is extremely quick to put together.
These days you can find sake, mirin, and even miso well stocked grocery stores. You may have to venture to a Japanese or larger Asian market to find yuzu kosho (or look online,) but it's worth it! Flat iron steaks come in various sizes, so you may have to adjust the amounts indicated to match the size. You'll want enough to coat the steak evenly in a thin layer. —Treble723
about 6 tablespoons
Miso paste (I used red, or aka, miso)
Yuzu kosho (start with a smaller amount and add to taste)
1 or 2 tablespoons
flat iron steak, about 2 pounds
In a small bowl, combine the miso, yuzu kosho (start with a small squeeze - about a centimeter or less), sake, mirin, brown sugar, and several grinds of white pepper. Taste and adjust for seasoning. You should get salty from the miso, sweet from the mirin and sugar, and a citrusy, spicy punch from the yuzu kosho.
Coat the steak evenly in the rub and allow to rest,covered, for at least one hour in the fridge. Grill until cooked to desired doneness (we usually go 4 or 5 minutes per side over a hot grill). Be sure to let it rest for about 5 minutes before slicing.