Unagi No Tare (Homemade Eel Sauce)

Unagi no tare, kabayaki sauce, nitsume—the glossy, syrupy glaze that adorns tender pieces of grilled eel—goes by several names and many preparations. And in truth, it’s mostly a restaurant thing. “No one would make unagi tare at home,” says author and Japanese food scholar Nancy Singleton Hachisu. “It’s really not a thing.” In part, that’s because when you buy unagi at the store, it already comes brushed in that iconic dark sauce, with a little extra in a packet for good measure.

Traditionally, nitsume(literally “boiling down”) was made from a broth of grilled eel bones, and even the liquor from steaming clams. To this broth, chefs added varying amounts of sake, mirin, soy sauce, and sugar, then reduced the mixture until it was thick and syrup-like. Presumably every chef had (or has) their own proprietary, guarded recipe for unagi sauce, employing variations in timing, ingredients, and texture.

These days, most restaurant chefs tend to eschew the eel-bone broth, and go straight for the other stuff: just sake, mirin, soy sauce, and sugar. Some even opt for the prepackaged, bottled sauce instead of cooking up their own. In restaurants that specialize in unagi, chefs are constantly basting and brushing eel throughout the day, using the same batch of sauce. And over time, this sauce takes on the grilled flavor of eel, so it develops additional savory depth, smokiness, and a slight brininess.

If you want to go the extra mile and make unagi sauce at home, the process can be quite simple. In the spirit of a more “traditional” method, this recipe utilizes a base of dashi, which adds umami and depth to an otherwise heavy-handed sauce.

Because you’re cooking the sauce to a syrupy consistency, and because there’s a significant amount of sugar here, it’s easy to overcook and even caramelize the sugar if you’re not careful. And while caramelization can be desirable in certain applications, it can also overpower more subtle flavors like those in dashi, or the wine from mirin and sake. So to prevent caramelization, it’s helpful to use a thermometer. I cook this sauce to around 235°F—within the range of a typical “soft ball” sugar stage (the point at which the cooked sugar syrup will cool to a solid but malleable consistency).

Out of the pot, this sauce might seem a bit runny. But it thickens as it cools, and assumes the perfect texture and viscosity for brushing and glazing meats. (If you prefer a thicker sauce, you can cook the sauce up to 240°F.) For best results, be sure to use a 3-quart saucier or larger with tall sides. The mixture will bubble and froth considerably, rising up the sides of the pot.