Musta Leiva Shoyu is a soy sauce-style condiment made with Estonian black bread rather than soybeans. The product is the result of a collaboration between Kristjan Jekimov, an Estonian-Korean chef and head chef of restaurant Sadu in Põhja-Tallinn, and Hiroaki Takeda, a Japanese-Canadian chef who spent nearly four years leading the kitchen at Lee Restoran, now Lee Brasserie in the Old Town.

For Takeda, using local ingredients was non-negotiable. "For me, it would not make sense to come to Estonia and make something that does not feature Estonian ingredients," he says. "Estonians are very passionate about supporting things that are Estonian."

Shoyu, the Japanese word for soy sauce, differs significantly from the mass-produced versions found in most grocery stores. Traditionally, it is made with soybeans, which are high in protein and produce an intense umami (savory) flavor. With Musta Leiva Shoyu, that base is replaced with Estonian black bread from the Muhu Leib bakery. Chosen for its caramel notes and naturally sweet, savory character, the bread connects Eastern fermentation techniques with one of Estonia's most iconic foods. It also produces a more flavorful and balanced condiment. 

Instead of fermenting the base with traditional koji rice, the chefs use koji made from Estonian barley. Koji, a cultivated mold fundamental to Japanese fermentation, transforms starches and proteins into sugars and amino acids, creating complexity and depth of flavor. Mixed with saltwater and left to ferment, the result is a shoyu with a character distinct from store-bought soy sauce.

"If you take black bread versus boiled soybeans, it is a huge flavor difference," Takeda explains. "The higher the starch content, the sweeter the end product." 

Takeda's interest in fermentation was shaped during his time studying at Copenhagen's Noma restaurant and deepened while leading the kitchen at Lee Restoran. There, a practical problem sparked experimentation: what to do with leftover bread. Muhu Leib supplied a custom black bread exclusively for the restaurant, and Takeda began fermenting unused loaves. Over time, those trials became the foundation for Musta Leiva Shoyu.

"That is how it all started," he says. "Moving forward, we will be using leftover bread directly from Muhu Leib."

For Jekimov, who cooked at Põhjaka mõis and Barbarea before becoming head chef at Sadu, the project resonated personally. With an Estonian father and a Korean mother, he grew up eating traditional Korean dishes adapted to Estonian ingredients.

"There are very traditional Estonian fermented products that people already know and love," he says. "Everybody knows their grandmother's version is the best. It already has its own life."

"What we want to do is show something different," Jekimov adds. "To bring our own backgrounds, but link them to Estonia, its ingredients, its people, and its flavors."

The chefs envision the shoyu being used well beyond sushi. While it works as a dipping sauce for sashimi or dumplings, Takeda says it is equally at home in salad dressings, marinades, or cooked into dishes like sauerkraut or fried cabbage.

With Musta Leiva Shoyu now available for sale, the duo is already developing their next product as part of a growing line of condiments focused on adding value to overlooked ingredients through Eastern fermentation techniques.

"Our goal has always been to expand the knowledge of Eastern fermentation techniques here," Takeda says. "That is the whole mission."

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