
Start with temple cooking and show the card elsewhere. One word settles it: dashi.
Japan has a long vegetarian tradition in its temples, and a modern food culture in which fish stock is almost everywhere. Those two facts pull in opposite directions, and it is worth knowing which one you are dealing with.
The thing to learn is one word: dashi. It is the stock in miso soup, in noodle broth, in simmered vegetables and in many sauces, and it is usually made from dried bonito — fish. A dish of vegetables can be entirely vegetable and still contain it.
That is not a reason to worry. It is a reason to ask specifically rather than saying “vegetarian”, because the word is understood but its implications for stock often are not.
“Oniku to sakana nashi” — no meat and no fish. The essential phrase.
“Katsuo-dashi nashi” — no bonito stock. This is the one that actually gets you a vegetarian meal, and the one nobody teaches you.
Show a card — see printable cards. It is faster and clearer than any spoken phrase.