Dark soy sauce

Aged longer than light soy and usually thickened with molasses or caramel. Less salty, noticeably sweeter, and viscous enough to coat. It is a colourant and a glazing agent, not a seasoning, and swapping it in for light soy under-salts a dish while turning it black. Used in small measured doses for exactly that reason: 5 ml for colour in a pale sauce, 10 ml to lacquer a dry pan of mince.