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Key Ingredient: Aaron Mooney marinates fish in shio koji

Challenged to create a dish with mold-inoculated rice paste, the Webster's Wine Bar chef takes advantage of its umami.



The Chef: Aaron Mooney (Webster's Wine Bar)
The Challengers: Carlo and Melvin Vizconde (Kai Zan)
The Ingredient: Shio koji

Writing about shio koji for the LA Times in 2012, food writer Betty Hallock noted that it's been called a "miracle condiment," the "new MSG" and the "next soy sauce." "Not bad for something that looks like beige sludge and smells like slightly sweet sweaty socks," she observed.

Koji, or cooked rice that's been inoculated with the mold spore Aspergillus oryzae, has been used in Japan for thousands of years; it's an essential ingredient in soy sauce, miso, sake, shochu, rice vinegar, and mirin. It's also used to make shio koji, where it's combined with sea salt (shio) and water and fermented for a week or so to create a pudding-thick liquid that's often used to marinate meats and make pickles.

Aaron Mooney of Webster's Wine Bar, challenged by Kai Zan chefs Carlo and Melvin Vizconde to create a dish with shio koji, says the ingredient can be used to replace salt but also reminds him of MSG. "It has more of that sweet, fermented, umami flavor rather than an abrasive saltiness," he says.

Aaron Mooney - JULIA THIEL
  • Julia Thiel
  • Aaron Mooney

Mooney used the shio koji to replace salt in an Asian-inspired dish: hamachi tartare with brined vegetables and sake-marinated citrus tobiko (flying fish roe). Because shio koji makes proteins caramelize faster, he says, he decided to serve the fish raw. He marinated it in a mixture of equal parts shio koji, lime juice, and olive oil for 15 minutes, explaining that he used the lime juice "to add a bright acidity and not so much of a sour acidity [from the shio koji]." The citrus tobiko that he soaked in sake and sprinkled on the marinated fish also contributed to the brightness of the dish.

Mooney vacuum-sealed raw beet, parsnip, and radish with shio koji and let it sit overnight so that the flavor would permeate the vegetables. He then rinsed them to get rid of any excess saltiness, sliced them thinly, and cut out a few disks of each to serve with the fish, finishing the dish with shiso leaves.

"I picked the radish to bring that spice element to it, the beet to have that earthiness, and the parsnip for sweetness," he says. "The shiso has a very herbaceous quality to it, with a little bit of bitterness."

The flavors of the finished dish went well together, Mooney says, though if he did it again he'd let the vegetables marinate a little longer in the shio koji so they could absorb more flavor. "I really like the contrast between the textures of the raw fish and then the really crunchy vegetables, the nice pop from the tobiko," he says.

Hamachi tartare with shio koji-marinated vegetables, tobiko, and shiso - JULIA THIEL
  • Julia Thiel
  • Hamachi tartare with shio koji-marinated vegetables, tobiko, and shiso

Who's next:

Mooney has challenged Greg Bastien of the Winchester to create a dish with pumpkin seed oil. He says the oil is "superintense, superbitter, and has a really great flavor when used in little amounts, so I wanted to see how he could make it the star ingredient."

Hamachi tartare with shio koji

4 oz hamachi, diced small
2 oz shio koji
2 oz lime juice
2 oz extra-virgin olive oil
Citrus tobiko roe
Sake to cover
Shio koji
Shiso (for garnish)

Cover whole, raw beets, parsnips, and radishes in shio koji and marinate overnight. Cover tobiko with sake and marinate overnight.

The next day, mix shio koji, lime juice, and olive oil spread, toss with diced hamachi, and let sit for 15 minutes. Rinse the vegetables and slice thinly. Serve fish with sake-marinated tobiko roe, sliced vegetables, and shiso leaves.

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