Put the ingredients in a bread machine. Complete the first rising and punch down on the dough.
Divide into 16 portions and cover with a tea towel. Leave to rest for 15 minutes.
Roll out the dough into rounds and wrap the portioned anko.
Seal the edges tightly.
Place the dough with the ends down and leave to rise a second time.
Proof until doubled in volume (do not over-proof).
Deep-fry in 160-170°C oil until golden browned. Refer to Hints.
Drop the doughnuts into the oil with your fingers or chopsticks gently to preserve its shape.
Drain excess oil on a paper towel and sprinkle with granulated sugar straight away. After cooling, sprinkle with powdered sugar to create a melt-in-your-mouth-like texture.
It looks like this cut in half.
Store the leftovers in a plastic bag as you do with bread.
Story Behind this Recipe
To make this recipe I referred to "Bread Loaf with 100% of Plain Flour and Whey" by user "Akkorin Mama" (Recipe ID: 401564). Using both granulated and powdered sugar gives it a pleasant melt-in-your-mouth texture.
How to deep-fry the doughnuts in shallow oil my way: Pour enough oil into the pot so the doughnuts do not to touch the base of the pot. After the first batch, add a little oil. By doing this, the temperature of the oil will drop and the doughnuts won't burn easily in shallow oil. If the temperature of the oil rises too much, try adding some new unheated oil to bring the temperature down again.