I liked this idea, even if it's not very green. But if you are in a hurry, making everything in one tidy packet is much quicker than trying to keep your hands wet so the rice doesn't stick to them. You also don't have to mess around with the onigiri form.
1) Mix the flavourings that you want into hot rice and turn it over a few times to cool it a bit.
2) Line a teacup or rice bowl with plastic wrap and fill with a handful of the rice mixture.
3) Push a little well into the centre and add your filling. I've used umeboshi (Japanese style pickled plums).
4) Twist the ends of the wrap together and form a ball with the rice working it together a little bit.
5) Using your first two fingers, form the three corners of the triangle.
6) Then you can untwist the plastic wrap and wrap it around the onigiri nicely so that it can be packed for lunch.