Omuraisu

Under a thin sheet of egg, butter-fried ketchup rice peeks through. Some shops wrap it around the rice while the egg is still soft and runny, others cook it through first and lay it over the top — either way, the steam and tang that rise when it's cut open are what draw people in. Chicken and onion are the standard filling, often finished with a drizzle of extra ketchup or demi-glace sauce, and the rice itself is usually seasoned with butter and salt before it ever meets the egg.

The base is rice fried in butter and seasoned with ketchup to make chicken rice, the usual method goes. Egg is beaten and cooked into a thin sheet, then wrapped around the rice while still soft. Some kitchens add milk or dashi to the egg for smoothness, others flip the whole pan to shape it — each shop is said to have worked out its own way of handling the egg, and some finish by slicing the top open at the table so the soft egg spills out.

One account traces it to a Ginza, Tokyo yoshoku restaurant in the Meiji era, where a cook is said to have combined an omelet and rice as a staff meal for a regular customer. Another traces it to Osaka in the Taisho era, where a shop is said to have wrapped ketchup rice in egg for a regular with a weak stomach. Both stories share a cook working out something for one particular customer, and from there the dish is said to have spread as a signature yoshoku item nationwide.