Here's what I learned so far:
- Original Krispy Kreme recipe had potatoes in it! See "Making Dough" By Kirk Kazanjian; which suggests that cooked potatoes, instant potatoes and/or potato starch would be ingredients to consider adding to the ultimate doughnut
- Many doughnut makers use pre-made mixes. One example of a mix is Spudos (50lbs for $50). In Spudos case, they don't include the yeast, but probably use powdered egg, powdered milk, potato powder and/or starch, sugar, salt, and flavorings.