Why This Recipe Works
The hallmarks of this San Francisco roll are its soft, chewy crumb and the mottled, crackly appearance that gives rise to its crunch. Developing a recipe for the soft, chewy crumb was the easy part. The topping—an odd mix of water, oil, sugar, salt, rice flour, and yeast—was the challenge. The ingredients need to be combined in the correct proportions to keep the paste from sliding off the dough once applied. A series of tests showed that letting the combined ingredients sit before brushing the topping onto the dough gave us dramatic crackling that was very flavorful. A 20-minute rest was best.