Eel Sauce Recipe

Combine the soy sauce, mirin, sugar, and sake (if using) in a small to medium saucepan. Stir briefly to dissolve most of the sugar before heating.

Place the saucepan over medium heat and bring the mixture to a gentle simmer. Watch carefully — mirin/sake can foam and boil over quickly.

Once simmering, reduce heat to low and let the mixture cook at a gentle simmer, uncovered, for 12–18 minutes. Stir occasionally to ensure sugar fully dissolves and to prevent scorching. The sauce should reduce by roughly one-third and become slightly syrupy. It will thicken more as it cools.

Thickening with Cornstarch (optional)

If you prefer a slightly thicker glaze, mix 1 tsp cornstarch with 1 tsp cold water to make a smooth slurry. Remove the pan from heat and whisk the slurry into the hot sauce. Return to low heat for 30–60 seconds, stirring constantly, until the sauce becomes glossy and slightly thicker. Do not overcook or the sauce may become too gelatinous when chilled.

Finish and Cool

Taste and, if desired, add a tiny drop (about 1/4 tsp) of toasted sesame oil for a hint of nuttiness. Allow the sauce to cool to room temperature; it will coat the back of a spoon and thicken further as it cools.

Storage

Transfer the cooled eel sauce to a sterilized jar or airtight container. Store in the refrigerator for up to 2–3 weeks. Reheat gently to loosen before brushing on grilled fish or sushi, or drizzle cold on rolls and bowls.