First: the rice. I honestly HATE cooking rice. I usually buy the frozen brown rice packages from Trader Joe's. However you like your rice, just start with that. Brown, white, leftover, premade, whatever. While the rice is warm add in a tablespoon of sugar, a couple tablespoons of rice vinegar and a little dash of salt. Stir this around to coat. It doesn't make sushi rice in it's truest form, but it makes a very similar taste with just a few ingredients hanging out in your pantry.
Once the rice is done and cooled, that will be your base. Then you can top your sushi bowl with whatever you like! I have two variations here, one I made for a fancier dinner in with my husband, and another I made packed into Tupperware for weekday lunches to bring to work.
Variation 1: I topped the "sushi" rice with sliced nori seaweed sheets (these have become so popular and you can find them anywhere), julienned (cut into matchstick size) cucumber, julienned carrots, avocado, toasted sesame seed, chopped scallion, krab (imitation crab used at most sushi restaurants for their California roll among others...find this in your seafood section), and premade ahi poke I found at my local Safeway. It was perfect! I served this with wasabi and soy sauce, of course, and topped with a little spicy mayo.
Variation 2: I packed Tupperware with "sushi" rice, nori, soy sauce, sesame, cucumber, scallion. Then I mixed imitation crab with a little mayo and a ton of sriracha for a take on a "spicy crab" salad. I added avocado once I was ready to eat. One of my favorite "to go" lunches to keep in the fridge!