Enjoy Prime Rib Like Never Before With One Umami-Packed Liquid

Whether you're preparing a roast for a holiday dinner or simply elevating a weeknight meal, prime rib is an elegant and delicious beef dish with a variety of different methods and techniques for preparation. Typically, using a dry rub on prime rib will yield a gently flavorful crust, but others might prefer to reach for their favorite liquid marinades instead. Meeting in the middle between those two different consistencies is a Japanese staple ingredient known as koji, which can be mixed with rice, salt, and water into a slurry called shio koji. A naturally occurring mold called Aspergillus oryzae, koji has a number of uses and, when mixed into a shio koji, makes a tongue-tingling marinade for your next prime rib roast.

Though it might sound offputting to be using mold in food, koji is widely used in the fermentation of many popular Japanese ingredients including soy sauce, miso paste, sake, and rice vinegar. Rather than mixing up your own slurry of shio koji from a powder, you can actually buy a bottled version of golden liquid shio koji such as Hanamaruki Liquid Ekitai Shio Koji (available on Amazon) for your own home cooking. The umami flavors present in this liquid make it the ideal marinade for your prime rib with a heavy punch of saltiness and robust taste. It's simple to use for a slow-roasted rib roast recipe, particularly when swapped in place of regular salt.

Using shio koji to brine your prime rib will both season and tenderize it for a deeper complexity of flavor. When buying prime rib, it's important to look at the grade of meat to find the best cut for your budget. A bone-in roast will yield a deeper flavor and it should ideally have a reasonable amount of fat that's evenly distributed throughout the meat. 

To prepare your prime rib, you could start by slicing thick pieces and coating them with the shio koji marinade for up to 24 hours, and then tying everything back together for roasting. Alternatively, leave the prime rib whole and brush the liquid over the surface. Remember that a little bit of shio koji goes a long way and you don't want to overwhelm your prime rib with excessive saltiness. A good rule to stick by is to use 10% by weight of marinade to the weight of your meat.

You can create a jus with the pan drippings and your favorite herbs and spices to accompany a perfectly medium rare prime rib. To lean further into the flavors inspired by Japanese cuisine, consider making a complementary side dish for your prime rib like tempura fried greens or a dish of oshinko pickled Japanese veggies. No matter how you decide you serve it, your shio koji-marinated prime rib is sure to impress.