The Origin of Tonkatsu / Okonomi Sauce

Fruit sauce aka okonomi sauce

I’ve wondered for a long time where Tonkatsu / Okonomi sauce in Japan came from. (By the way, Tonkatsu and Okonomi sauces are essentially the same.) This sauce is commonly used in Japan for breaded pork cutlet (tonkatsu), okonomiyaki (savory pancake), and takoyaki (octopus ball). The reason why the origin of this sauce was hidden from me for a long time is because the common usage in Japan is completely removed from the common usage of its ancestor, which I believe is Indian tamarind sauce.

Wikipedia claims that its ancestor is Worcestershire sauce, but Worcestershire sauce itself is derived from Indian tamarind sauce. So, the question is whether the Japanese got it from the British or from the Indians. It’s hard to say because the common usage in Japan is completely different from how the British use Worcestershire sauce. Nobody I know uses Tonkatsu sauce for steaks. And, who in the West use Worcestershire sauce for breaded pork cutlet?

The break-through came when I remembered the dinner I had at a friend’s house when I was a sixth grader in Japan. They served Japanese-style curry that night, and they poured Tonkatsu sauce over the curry. My family has never done that, and I haven’t seen anyone else do it either, but my friend’s family did it as if it was a perfectly normal thing. Now I think about it, perhaps it was indeed a normal thing to do. If you think of tonkatsu sauce as the Japanese version of Indian tamarind sauce, it makes perfect sense to serve it with curry.

Unfortunately I lost contact with this friend so I cannot ask him where they got the idea from, but I’m now leaning towards the idea that Tonkatsu sauce came directly from India, not from England.