The ginkgo nut is the pale, chewy, nut-like seed found inside the foul-smelling fruit of the ginkgo tree, a living fossil that has barely changed in 200 million years. Shelled and boiled to a translucent jade green, the kernel is faintly sweet, slightly bitter and resinous, a prized morsel in East Asian chawanmushi, congee and hot pots — eaten only in small amounts because it is mildly toxic in quantity.