Sourdough Hokkaido Milk Bread

I've been on a bread making kick this year. My favorite bread is a sourdough wheat walnut bread and I'm working on my own version, but after six loaves in a row, I decided to take a break and try making a different bread. I saw an amazing photo of soft Hokkaido Milk Bread and used the accompanying recipe.

Hokkaido Milk Bread is supposed to be a very soft sweet fluffy bread. The recipe I followed used a sourdough starter instead of commercial yeast and omitted the tangzhong, a roux-like paste, that seems to be used by most recipes. This was my first time working with a very wet rich dough, enriched with butter, sugar, milk, cream and egg whites. It was so sticky and wet! Most recipes seem to use a stand mixer so I had difficulty figuring out how to develop the gluten by hand. I tried to rest the dough then do stretch and folds like I've been doing with my normal sourdough bread, but the dough refused to behave and was still ridiculously shaggy. I gave up and added a bunch of extra flour, but though the dough got stiffer, it was still so sticky and the gluten wasn't developing. Finally I found this video on kneading rich dough by hand. After probably 45 minutes of slapping the dough down, stretching and folding, the gluten structure finally started developing and the dough came together. Now I know what to do next time.

The proofing loaf rose slowly but steadily. Then in the fridge overnight, it got super tall. Unfortunately, that was mostly due to a ginormous air bubble. Slightly strange shape and I'm not sure it rose as much as it was supposed to, but the crumb is soft and deliciously sweet with a slight sour tang. I'm looking forward to seeing how it looks when I make it again.