The california roll is one of the most favored sushi rolls and has been credited with popularizing sushi in the united states. California rolls are usually made inside-out rice on the outside, nori (seaweed) on the inside making them easier to eat. The center is studded with crab meat or imitation crab, cucumber, and avocado. There is some debate as to where the california roll was invented. Most people believe that a sushi chef at a little tokyo restaurant in los angeles came up with the idea. However, a canadian sushi chef takes the credit, claiming he named the roll "California" Due to its popularity with southern californian guests. You will need a bamboo mat to roll the sushi, which is found at asian markets as well as some supermarkets. The technique for rolling sushi isn't difficult but may take a little practice. Once you master it, you will be able to create any type of sushi you like.