Katsudon

The most widely cited origin story dates to 1921 at the Waseda soba shop Sanchoan, attributed to a student-regular named Keijiro Nakanishi — though it is one of several competing claims (Sanchoan's own lore puts the egg-bound version a few years earlier, c.1918, and another theory traces it to Kofu, Yamanashi, c.1897). The story: Nakanishi proposed repurposing pork cutlets left over from a banquet by simmering them over rice — and sources disagree whether his version was egg-bound or simmered in Worcestershire-style sauce with flour. The dish spread fast through Tokyo's student-cafeteria culture in the 1920s-30s as a cheap calorie bomb before exams. Superstition since: students eat it for luck because 「カツ」(katsu) sounds like 「勝つ」 (to win).

Waseda University's Sanchoan claims the 1921 invention — pork cutlet simmered briefly in dashi-shoyu-mirin with onion and egg, ladled over rice. The katsu must be panko-fried first, never raw-simmered.

A bowl of hot rice topped with tonkatsu (breaded fried pork cutlet) that's been simmered briefly in dashi, soy, mirin, and sliced onion, then bound with a half-set beaten egg poured around the edges. The cutlet stays partly crisp where it sticks up out of the broth, and goes soggy-savory where submerged — that contrast is the dish. The egg should be wobbly, never fully set; a hard egg means it overcooked.

The cutlet must hit the simmer immediately after frying — within minutes. A cold tonkatsu in dashi turns into wet bread; a hot, just-fried one absorbs broth at the cut surface while the breading still has integrity. Most home failures are reheating yesterday's tonkatsu. The egg goes in twice in some Tokyo shops: half first to bind, half at the very end so the top stays liquid — an old-school move now rare.