We've been calling the green leaves "sesame leaves", but some searching makes it sound like they're perilla or shiso in Japanese. Basically, it's Japanese basil. It seems like whenever we get tempura at restaurants this is always one of the bits you get.
We laugh now at our horrible attempts at tempura before we came to Japan. We're no experts now but we know enough to use ice water when making the batter and not make it too thick. We're not making onion rings - although, in a sense, we are, aren't we? Yummy!
We're obsessed with this tempura paper that we buy at the dollar store which soaks up the oil. Also at Daiso we buy oil filter papers so we can clean and reuse our oil. Brilliant.
The sauce we make is just a basic tempura sauce, but it tastes like Japan to us now. I think it's this recipe. Japanese sauces are really sweet. We use a vegetarian dashi stock bouillon cube we get at the organic store the next town over.