Very interesting topic! I've been thinking about mcdonalds fried pies lately, which have a similar outward texture-in McDonald's case, I'm pretty sure the dough has been dusted with starch before frying to create the blisters, such as corn or wheat starch. And this is an interesting link:https://www.google.com/amp/s/mylastbite.wordpress.com/2009/05/14/trisol/amp/?client=safari
Best of luck, keep us posted!