I learned a great trick for making grilled rice balls from my friend Elizabeth of Taste of Culture fame. It’s not exactly a recipe, but a procedure.
When you have leftover rice (the slightly sticky, short grain Japanese kind), make rice balls by pressing the rice in your hands to form a ball or a triangle about two fingers thick and the size of the center of your palm. You can tuck some pickled plum or other tidbits inside if you like. Wrap them individually in plastic wrap and freeze them. They will survive about six weeks in the freezer.
When you’re ready to eat them, take them from the freezer and place them on a stove top grill pan. The Japanese ones have a wire mesh over a square pan to diffuse the heat. Cook the omusubi on one side until they no longer stick to the grill (you have to be patient and not test them too often or they will fall apart), then flip them over and toast the other side. Brush with soy sauce, grill another few seconds to let the sauce mellow. Serve with a sheet or slice of nori.
This is explained in more detail with better delivery in Elizabeth’s forthcoming book, Washoku, Recipes from the Japanese Kitchen, to be published this fall by Ten Speed Press.