Unagi sauce (うなぎのたれ) or eel sauce is a thick soy-based sauce with a golden-brown color, prepared with caramelized sugar. Eel sauce, also known as kabayaki sauce, is a thick, sweet, and spicy sauce popular in Japanese cuisine. Despite its name, it does not actually contain eel and is typically used as a glaze for grilled eel dishes such as unadon (grilled eel with rice) or unagi nigiri (sushi with grilled eel). The main ingredients of eel sauce are typically soy sauce, mirin (sweet rice wine), and sugar (although for variety, sake is sometimes added for more complexity), as well as dashi (mackerel flake broth or kombu). These ingredients are simmered together until the sauce thickens to a syrupy consistency with a glossy surface. The result is a dark brown sauce with a rich and complex flavor that combines the sweetness of mirin and sugar with the savory saltiness of soy sauce. The Unagi sauce flaunts a distinctive caramel flavor with hints of umami and is used to add depth and richness while enhancing the natural flavor of eel and providing a sweet and savory balance.