Put the ☆ ingredients in a bowl, pouring gradually as you stir. Mix well so as not to leave lumps.
Once it's well combined, strain.
Transfer the mixture into a heatproof container (or empty milk carton) and cover with plastic wrap, but leave 1 cm or so from the sides unwrapped.
I just pour the mixture straight into a container while straining it in Step 2 since I like to cut corners.
Set the power to high and microwave for 7.5 minutes. (500W) The time depends on the microwave, so check the mixture as it heats.
It will be a bit sticky at first, but it will set as it cools. If you microwave it for too long it will turn hard, so be careful!! I have done this before...
When the cake cools, cover with plastic wrap again and place in the fridge.
Remove from the container and cut into your desired sizes. It's fun to take out from the container as it jiggles.
Story Behind this Recipe
I used milk cartons as a container at first, but I had to get heatproof glassware as my family requests this a lot. My container now is a Pyrex pound cake pan (18 x 8 cm).
For white uiro with azuki red beans, the recipe will be 110 g cake flour, 50 g sugar, about 1/3 of a can of azuki (adjust to your liking), a pinch of salt, and 300 ml water. Neither the brown sugar nor azuki uiro is too sweet, so adjust the sugar to your taste.