How do I stop onigiri from falling apart?
Things to try


Rice should still be warm
Handle rice gently, don't squeeze it


Does it fall apart because it is sticking to your hands? If so:


Use warm salt water on your hands (not dripping wet hands though)
Rinse the rice more before cooking to remove excess surface starches. The process is: Rinse in bowl of water, gently tumble, let stand 20 minutes, change water. Repeat until rinse water runs clear


If this still fails to solve this sticky issue, you can use cling film (plastic wrap) as a guide and release agent on your hands. Peel the plastic off as you wrap the nori on