The white strawberries are a variety called Mara des Bois, and they taste more like tutti frutti than strawberries. They do not grow to the size of the strawberries you get at the grocery store, but then again, those strawberries have little flavor. I got these white strawberries at the Sebastopol Farmers Market from Nancy at Middleton Farms. She is an amazing producer, always has quality stuff.
On to the onigiri lesson! You can click on the images for a larger view. (Figure 1) The onigiri mold has removeable bottoms and a lid that comes off. Many people recommend wetting the onigiri mold before filling it. Water, or water with some salt in it will help keep the rice from sticking to your mold. (Figure 2) Fill the mold about 1/3 of the way with cooked rice. I use cold rice, but you can use warm rice too. (Figure 3) If you want to, put a small bit of filling in the center of the rice mold. I used leftover barbequed brisket from BBQ Smokehouse in Sebastopol, hands down the best BBQ in Sonoma County. Do not use really wet fillings as they will leak out of the onigiri. (Figure 4) Fill the mold with more rice until you are a little bit over the top of the mold, but to not pack it in, just lightly fill it. (Figure 5) Place the top of the mold over the rice and press firmly straight down. If you have not added enough rice, carefully remove the lid and add a bit more. Carefully remove the top lid after the shape has been molded.
(Figure 6) Gently push the bottom of the mold up through the opening at the top of the mold. (Figure 7) You'll see that the heart shaped onigiri is carefully making its way out of the top of the mold. (Figure 8) Once the rice ball is free of the mold, carefully remove the bottom piece of the mold from the rice ball. (Figure 9) Place the onigiri in your bento box and embellish it with sesame seeds or a cute soy paper cut out.
I have cutters in different shapes for cutting soy paper or nori (seaweed) in cute shapes. Soy paper and nori can be found in asian markets and also at Sonoma County's G&G Shopping Centers.