Cut the mochi into sixths. Heat in a toaster oven until they plump up.
The mochi should plump up like this. You can also do this in a microwave, but the mochi will harden. That's why I recommend using a toaster oven.
While the mochi is heating up, put all the other ingredients into a mug and mix. Microwave for 1 minute to heat. (Please adjust the heating time.) Add the toasted mochi to finish.
How to Preserve Boiled Adzuki: Fold back the open end of the zip-bag and put the adzuki inside. Press out the air and close the bag.
Draw a dividing line with a chopstick, and store in a freezer. You can break a piece when you're using it to make zenzai. Put it into a mug, mix it with milk, and microwave it.
Story Behind this Recipe
I had lots of canned boiled adzuki and mochi. If you have any leftover heavy cream, try adding it into the mug using a piping bag. As if you're drinking hot chocolate. This is also amazing.
Because I used a 500 g can of adzuki, I was left with 450 g more. So I divided it into ninths and froze it to use each piece (50 g) later to make a mug of zenzai. It allows me to make it any time I want. When you're using the adzuki for other purposes, take out as much as you need and let it defrost at room temperature or with the 'defrost' setting of your microwave. Please add condensed milk to your liking.