Japan — Tokyo, Meiji-Taisho era; derived from the yoshoku tonkatsu culture; donburi format applied to tonkatsu; the name is a portmanteau of 'katsu' (tonkatsu) and 'don' (donburi); associated with university exam tradition from Showa era
Katsudon (カツ丼) is one of Japan's most beloved and comforting donburi (rice bowl) preparations — a tonkatsu pork cutlet simmered briefly in a dashi-soy-mirin sauce with sliced onion and then bound together with a soft, barely-set beaten egg, poured over a bowl of white rice. The technique requires precision timing: the egg must be added at exactly the right moment — when the sauce has concentrated and the onions are soft — and cooked with the lid on for exactly 30–40 seconds before the bowl is assembled, producing a custardy, partially-set egg that continues cooking from residual heat as it rests on the rice. Katsudon is so beloved that it is the traditional meal eaten by Japanese students the night before university entrance exams (katsu = to win/succeed).
Rich tonkatsu flavour absorbed into barely-set sweet egg, dashi-mirin-soy broth, caramelised onion sweetness, white rice as the neutral base absorbing all these elements — deeply satisfying, sweet-savoury comfort food
The cutlet is sliced before adding to the pan — 1.5–2cm diagonal cuts, maintaining the overall form. The sauce ratio: approximately 100ml dashi, 1.5 tbsp soy sauce, 1 tbsp mirin, 1 tsp sugar per serving. Add the sliced onion first and cook until soft (2–3 minutes). Add the sliced tonkatsu. Beat 2 eggs per serving, pour over the cutlet and onion mixture in a circular motion. Cover immediately with a lid. Cook 30 seconds — the egg should be visibly set around the edges but still runny in the centre. Slide onto hot rice immediately without overcooking.
The professional technique: use a small individual oyako-nabe (single-serving oval pan) for each portion — the straight sides and small size allow perfect egg-to-cutlet ratio control. The rice beneath the katsudon should be freshly steamed and slightly firmer than standard — it needs to absorb the sauce that flows from the egg without becoming mushy. A sprinkle of togarashi chilli powder and a side of pickled red ginger (beni-shoga) are the canonical accompaniments.
Over-cooking the egg — the egg must be liquid in the centre when removed from heat; it will set further from the heat of the rice and sauce. Under-cooking the onions before adding the egg — they should be soft and slightly sweet. Using leftover tonkatsu that has been refrigerated — the cutlet must be warm enough to interact with the egg and sauce properly; reheat it gently in the sauce.
Tsuji, Shizuo — Japanese Cooking: A Simple Art; Japanese donburi culture documentation