On Saturday, I made Onigiri to go with the Cabbage Nori Rolls I served to my family and our young guest. Though the rolls didn’t contain any rice, Onigiri are virtually all rice. They’re made by simply cupping sticky, hot sushi rice in your hand and pressing it into a triangle or other shape around a filling. I filled the round ones you see on the right side above with dried shiitake mushrooms that were re-hydrated and marinated briefly in miso and sesame oil (2 tbsp. water. 1 tsp. light miso, 1/8 tsp. sesame oil), and then rolled them in black sesame seeds. The vaguely triangle-shaped ones contained pieces of baked tofu and are wrapped in a piece of nori (wet it first).
I don’t have a real recipe for this but I do have some suggestions:
First, make sure your rice is very sticky. I cooked mine as I usually do for sushi, and it wasn’t quite sticky enough. I suggest adding a little more water than the package indicates.
Second, keep your hands wet as you mold and press the rice together. Sticky rice is, you know, sticky: it will cling to your hands and prevent you from making smooth shapes, but the water will keep it from sticking to you.
Finally, use a strongly-flavored food as the filling. Traditionally, umeboshi plums are used, and they have a very strong taste. My shiitake mushroom filling tasted much better than the tofu filling, which got lost in the middle of all that rice.
You can get more directions (and photos) for making onigiri at this site. Have fun!