Like so many other brilliant ideas, this one started as a scribble on a napkin. From there, chef-partner Brian Ahern’s brainchild grew into a three-day procession of seasoning, searing, braising, and deep-frying in beef fat — and it ended up a Chicago-by-wayof- the-bayou classic. The beignets make a compelling case that every doughnut would be better if you stuffed beef inside it.