Start to soak both beans 2 nights before baking day with 4/3 cups of water. See how to make bean paste in two separate posts. *2
This amount makes about 160g (5.6oz) each of Azuki and White bean paste.
Make yudane a night before baking day. Place the bread flour in a small mixing bowl and pour in the boiling hot water. Combine them with a wooden spatula.
When it is cooled down, wrap with cling wrap and leave it on the kitchen bench in winter or leave it in refrigerator in summer.
Making Anpan Bread
Combine the milk, egg, sugar, instant dry yeast, bread flour and salt in a bowl of a stand mixer. *3
Set the stand mixer with a hook attachment and knead for about 15 minutes. *4
Add the butter and continue to knead a further 15 minutes. *5
Roll the dough round and place the dough into a greased bowl. Wrap with cling wrap to rise for about 45 min to 1 hour at about 86°F (30°C) or until double the size. *6
Divide the bread dough into 12 equal sized balls and let them rest on the kitchen bench covered with well wrung out damp cloth.
Meanwhile, divide the sweet bean pastes (azuki and white) into 6 equal sized balls (so all together 12 ) and set aside.
Roll out one dough ball until it is slightly flat and place one white bean paste ball in the centre, then mold the dough around it to form a bread roll. *7
Repeat for the remaining dough and all bean paste balls.
Place them on a cooking paper lined oven tray and cover with a clean damp cloth for the second proofing for about 20-30 minutes or until doubled in size again. *8
Preheat the oven to 356°F (180°C)
Gently brush with beaten egg or milk, and stamp with sesame seeds.
Bake in the preheated oven for 20 minutes.
Remove from oven tray and cool them on a cooling wire rack.
*1 Average weight of large egg is 50 g *2 Azuki Bean Paste recipe and White Bean Paste recipe*3 I used a Kitchenaid brand stand mixer set on speed 4-5. You can also hand knead manually. *4 Set speed 4-5.*5 You can do the finger window test. The dough should be smooth and elastic. You would be able to see through your fingers. *6 If your oven can't set 86°F (30°C), you can create the environment with a styrofoam box with two cups of hot water in it as the photo indicates in above post) *7 See the tip in the post for how to roll uniformed thickness bread buns.*8 Or you can place rolled buns in a muffin tin for the second proofing. *9 The making of sweet bean paste and yudane time is not included in the total time of making Anpan.