What it actually is
Curry udon takes a thick, mild Japanese curry sauce — closer to a curry-flavoured broth than the drier, richer curry served over rice — and pours it over thick udon noodles, often with a splash of dashi stock mixed in to loosen the texture and add umami depth. The result sits somewhere between a soup and a curry, eaten with chopsticks and a spoon.
Why Osaka specifically
Udon has deep roots across the greater Kansai region, and Osaka's noodle shops have long treated curry udon as a genuine specialty rather than a novelty menu item, often served with a soft-boiled egg, a piece of fried tofu (aburaage) or a scattering of green onion on top.
How to order and eat it
It's typically ordered exactly like any other udon dish, and the biggest tip is one every local knows and every visitor learns the hard way: the sauce splashes far more readily than a standard broth, so a bib or care with white clothing is genuinely worth considering.