Place the cooked rice into a mixing bowl and sprinkle on the furikake. You can use as little or as much as you'd like. Mix together.
To Make the Onigiri: wet your hands in the water; this is just to keep the rice from sticking to your hands. Next, sprinkle on some kosher (or sea salt) salt onto your hands. The salt helps to flavor the onigiri. Start with just a little salt, make one and adjust as needed.
Scoop about a 1/2 cup of the cooked, warm rice (1/3 cup if you want to make them smaller) and, using both hands, form and shape the onigiri into a triangle. Don't use too much pressure but just enough to form and shape the rice. It doesn't have to be perfect. I also like to have a cutting board, or flat surface near by and will gently press the onigiri on the sides to help make a more distinct triangle shape. You can also buy Onigiri molds online.
Place one piece of the nori on the bottom (as shown in the photos) and sprinkle on some sesame seeds if desired. Continue until all of the rice balls are complete. Enjoy immediately or wrap each one individually with plastic wrap. These can be made in the morning and eaten later in the day. They are best eaten day of! Enjoy!