vegetarian sushi

Not all sushi has meat or fish in it. It's entirely possible to make delightful sushi with all vegetarian ingredients. Lately, vegetarian sushi has been my favorite. The reason I consider it "advanced" is because in order to make the two examples I show here, it takes either precision with a knife or careful attention to texture when steaming. It's worth the trouble, though, and here's a few examples.
Start with a cucumber. Normally I'd prefer to use an English cucumber but there's a bit more meat in a US type cucumber. Using a very sharp knife, uniformly cut around the cucumber. You want it to be as uniformly cylindrical as possible.
Cut off the ends.
Start a slit, and slowly cut layers off of the cucumber going around in circles. You want a nice uniform sheet of cucumber to use as an alternative to nori.
Here's the sheet of cucumber "nori".
It's not very easy to use a rolling mat to get tight rolls, so do it by hand, and be very gentle. Here I have sushi rice and avocado rolled in my cucumber sheet.
Here I'm steaming mini bell-peppers cut in half lengthwise, and there's asparagus on the lower level of the steamer basket.
Steam harder vegetables long enough to make them tender.
The finished product here, nigri sushi using vegetables. The colors, flavors, and presentation makes it worth it to try vegetarian sushi at least once.