My first few years in Japan saw me imbibe more than my fair share of substandard sake. This self-flagellation included everything from single-serve 7-Eleven cups to atsukan (hot sake) at karaoke, the cost-to-alcohol ratio always the chief consideration.

In large part, it took the generous tutelage of a befriended sushi chef to open my eyes to the nuance of nihonshu (Japanese rice wine) and the pairing possibilities therein.

Nihonshu is deceptively simple. The terroir that the water and rice each impart are important. However, the most complex flavor component, arguably, is the kōji, the cultivated mold that converts rice starches to sugar (via the amylase enzyme). This saccharified starter is then fermented to become alcohol in a beer-like process. Floral or fruit notes? Those come from kōji.

Kōji is used in washoku more broadly wherein proteins are transformed to glutamate (via the protease enzyme). Beans are fermented into ubiquitous pastes and sauces, and katsuo (skipjack tuna) is cured to katsuobushi (dried bonito shavings), to name but a few. For more on the science, check out the book “Koji Alchemy” by Jeremy Umansky and Rich Shih. Over and above expected applications, they’ll have you blurring borders with everything from supercharged baked goods to fuzz-covered hyperspeed charcuterie — both animal and vegetable.

If you’ve passed through phases of adding soy to everything, and in turn miso, kōji is the next frontier. Premade products will add umami from an external source, but kōji will bring it out from within, adding nuance to the raw ingredients themselves.

Behold the unassuming onion bulb. Upon pondering which ingredient epitomizes the interplay of sweet and savory, the perennial tear-jerker is unparalleled. The omnipresent singularity of culinary trinities the world over, they’re also Maillard’s exemplar extraordinaire. Acted upon by kōji, time and heat, they cook down to form an umami-rich, yet sweet, topping for my second-favorite Italian flatbread.

“Flour, oil, heat, umami” could be a book title by American chef Samin Nosrat and what follows is basically an enriched sourdough homage to her Ligurian loaf — I highly recommend her TV series and book “Salt, Fat, Acid, Heat.” In place of brine, to keep the bread moist we’ll use shio-kōji paste to release liquid from within the onion that then becomes a jammy glaze.

Pour the onion shio-kōji mixture over top in an even layer. Liquid should pool in the valleys you’ve created. | SIMON DALY
Pour the onion “shio-kōji” mixture over top in an even layer. Liquid should pool in the valleys you’ve created. | SIMON DALY


Makes 1 large loafPrep: 15 mins. + 6 hours waitingCook: 25 mins.


  • 200 grams fed sourdough starter (primer)
  • 1 large red onion (or 200 grams mini tomatoes)
  • 2 sprigs of thyme
  • 100 grams shio-kōji
  • 400 grams warm water
  • 10 grams instant yeast
  • 600 grams “rustica” bread flour
  • 10 grams salt
  • 20 milliliters olive oil or melted butter


  1. Three days before baking, take 1 teaspoon of sourdough starter and feed it 15 grams of flour and the same amount of water. Repeat additions the next day at 30 grams each, 60 grams each on day three.
  2. On baking day, thinly slice the onion and, in a small bowl, mix with the thyme and shio-kōji. Cover with a tea towel.
  3. In a very large bowl, mix the starter, warm water and dry yeast together, leave for 10 minutes until creamy.
  4. Mix together the salt and flour and add to the yeasty water. Combine until nearly uniform, but don’t knead.
  5. Cover the bowl with another tea towel and leave it in a warm place to rise for four hours to double in size.
  6. Line the bottom of a high-sided baking tray (at 36×24×7 centimeters) with kitchen paper and pour the olive oil onto the paper.
  7. Turn the bread onto the oil, coating it, and fold it twice, making sure the outside is covered in oil. Press lightly to flatten.
  8. Proof in a warm place for 40 minutes.
  9. Dimple the focaccia with your fingers, flattening it toward the tray edges. Pour the onion shio-kōji mixture over top in an even layer. Liquid should pool in the valleys you’ve created.
  10. Let rise for another 40 minutes and preheat your oven to 220 degrees Celsius. If you have a pizza stone or steel, use it.
  11. Bake the bread for 25 minutes until the edges are golden and the topping is sugary shiny. Remove it from the pan to a wire rack and slice to serve warm or cooled.

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