Motoyaki is a Japanese-derived cooking style in which seafood, such as oysters, scallops, or lobster, is baked in its own shell under a rich, mayonnaise-like sauce until the top browns.
The sauce, sometimes called tamagonomoto, is made by beating egg yolks with oil the way mayonnaise is made, without vinegar, and is often flavored with miso or soy sauce. It is spread thickly over the seafood before the dish goes under a broiler or into an oven, giving the top a golden, slightly caramelized crust while the seafood underneath stays moist.
Motoyaki is common on Japanese restaurant menus in North America, particularly on the Pacific coast, more so than in Japan itself. It is often confused with teriyaki, but the two are distinct: teriyaki is a soy-mirin glaze brushed onto grilled meat or fish, while motoyaki is an egg-and-mayonnaise sauce baked onto shellfish.