Warabi-mochi (potato starch jelly)

Sounds wrong I know but this is a very typical Japanese sweet.
Originally made by the warabi (blacken) starch, but that was long ago, before potato start to grow in Japan. Now a days this is usually made by potato starch.

For early Valentine's day, I made this for my boys in heart shape with my love and care.

Then they came back to me saying it's too sticky and difficult to cut.
Hmmm. After all, I had to cut the hearts into small pieces.

This tells something, doesn't this?
What they don't know is, I reserved some out from each dish; my love has been deducted.
Recipe is deadly simple finishes in 10 minutes - this also tells something....
* Eat them immediately as it gets dry and hard if you leave it long.

<Ingredients>
50g sugar
100g potato starch
150ml cold water
some kinako: soy beans powder
some matcha green tea powder
additional sugar if you prefer sweeter

<Tools>
a microwave safe bowl - like a soup bowl
a flat plastic container which can fit all above in one - something like a takeaway container (not a paper doggy bag in USA style)

<Method>
1. Mix all ingredients in a microwave safe bowl. It melts quick and easy.
2. Put the bowl in a microwave for 30 seconds, then carefully take the bowl out, mix the contents.
3. Put the bow again in the microwave for 30 seconds, then carefully take the bowl out, mix the contents. - it should be getting slightly hard around the bowl, scratch them and mix them all.
4. Put the bow again in the microwave for 30 seconds, then carefully take the bowl out - (I'm not trying to make the recipe longer), just repeating again but now the mixture must getting stickier and harder to mix. still mix them well.
5. Put the bow again in the microwave for 30 seconds, then carefully take the bowl out - now the mixture should be really sticky, no liquid remained, and slightly transparent. mix them again, take the mixture out to your plastic container, spread the mixture in the container to be flat. Be careful, the mixture must be very hot and will stick to your hands; Use 2 wet spoons, one to hold one to push.
6. Once the mixture is flat in the container - doesn't need totally flat or fitting until corner - then bring the container to under running cold water. Don't worry, it won't melt. Cooling down by the cold water, the mixture start to get clear. once it's enough cold to handle it, take it out on cutting board and cut them in about 2cm square or what ever the shape you prefer (but not too big shape like my heart because difficult to eat).
7. Serve it with some kinako (soy beans powder) or green tea powder on with some sugar if you like them more sweet.
* Be aware this sweet is sticky.
* Eat them immediately as it gets hard if you leave it long.