Kombu no Tsukudani (昆布の佃煮) — Soy-Simmered Kelp Relish

• 60 gdried kombu (or 160 g hydrated kombu left from making kombu dashi)
• 600 mlwater
• 60 mlJapanese soy sauce
• 45 mlmirin
• 45 mlsake
• 24 ggranulated sugar
• 15 mlrice vinegar (helps tenderize the kombu)
• 9 gtoasted white sesame seeds

Instructions

1. 1

   Wipe the dried kombu lightly with a clean damp cloth to remove grit, but do not scrub away the natural white surface bloom because it contains savory compounds. Place the kombu in a bowl with 600 ml water and soak for 15 minutes, or use 160 g already hydrated kombu if it has just been used for kombu dashi.

2. 2

   Lift the kombu from the soaking water and reserve 120 ml of the soaking liquid for simmering. Cut the softened kombu into strips about 3 cm long and 5 mm wide, or into small squares if you prefer a rice-topping texture.

3. 3

   Put the cut kombu, reserved 120 ml soaking liquid, soy sauce, mirin, sake, sugar, and rice vinegar into a small heavy saucepan. Stir once to dissolve the sugar, then bring the mixture to a gentle simmer over medium heat.

4. 4

   Reduce the heat to low and simmer uncovered for 35 to 45 minutes, stirring every 8 minutes so the kombu cooks evenly. The liquid should reduce slowly to a glossy glaze, not boil aggressively, because hard boiling can make the kelp tough and salty before it becomes tender.

5. 5

   When only about 1 tablespoon of syrupy liquid remains in the pan, stir more frequently for 2 to 3 minutes to coat every piece of kombu. Remove the pan from the heat before the glaze dries completely, because the residual heat will continue thickening the sauce.

6. 6

   Fold in the toasted white sesame seeds while the kombu is still warm. Cool to room temperature, then serve in small portions with steamed rice or transfer to a clean container for refrigerated storage.