Tempura here in Canada/BC whatever is just so boring and gross. Our local sushi restaurant does a slice of yam, a slice of potato, and a slice of eggplant: BORING. Even at other sushi/japanese restaurants I've been to since being back from japan the tempura is always prawn heavy (b/c us north americans love our meat!) and is just yam or zucchini or eggplant probably because north americans don't like "weird" vegetables (and i guess if you're running a restaurant you dont want to take any risks).
The tempura I had in Japan (even the kind from the grocery store's deli) was always Amazing. I remember this one place in my community that made fresh soba noodles, that we ate cold with a wasabi and shoyu bath. and it came with fresh tempura, so light and crispy! and with local vegetables (never meat). there would be heavy greens (like kale), and mushrooms, and taranome, and the littlest japanese eggplants, and thin slices of kabocha squash with the skin still on. those were my favourite.
When we hosted sustain-a-table the other week and served japanese food, one of the things I made sure to serve was squash tempura. I had a massive hubbard that i sliced into thin (2-3mm) slices and coated in boxed tempura (i was being lazy b/c i was in a rush and didn't want it to screw up, but i've made it from scratch and it's just as good!). then i deep fried it. pretty simple. i fried them until they were golden. we ate them hot with a veg shoyu mix. to die for.