Onsen tamago — Japan

Onsen tamago takes its name from the Japanese words for hot spring, onsen, and egg, tamago, literally meaning "hot spring egg." It describes an egg cooked in water that stays below boiling, which produces a texture between hard-boiled and soft-boiled: the yolk sets to a thick, custard-like consistency while the white remains soft and only lightly set. The technique is named after the practice of cooking eggs directly in the naturally hot water of thermal springs, where the steady, moderate temperature suits this kind of slow coagulation. The same term is now used more broadly for any egg cooked this way, whether or not an actual hot spring is involved, since home cooks and restaurants reproduce the temperature with a pot of water and a thermometer. To prepare it, eggs are lowered into water held at a steady temperature, well below a full boil, and left to cook gently for around 15 minutes. During this time the yolk proteins set before the white's, which is the reverse of what happens in ordinary boiling, and explains the dish's particular texture. A light dashi-based sauce, seasoned with soy sauce and mirin, is often prepared alongside and poured over the egg once it is cracked into a small bowl. It is served warm, usually on its own or over rice, and garnished with sliced scallion or a few flakes of dried bonito. Because the texture depends closely on temperature and timing, small variations in either produce a noticeably different result from one attempt to the next.