Teff. It's a tiny seed from the Horn of Africa, and makes for a tricky flour that is high in nutrients and protein. If not careful and properly used, Teff can stick in your banneton, an expensive proposition for such an expensive but delicious grain.
Recently I attempted a formula that comes from SFBI, who have been my latest portal to ancient grain baking. Since first tasting some of the ancient grain breads while attending classes there years ago, I've attempted baking this particular Miche variety, mostly because of its delicious flavor profile. So far, two attempts have been a dismal failure, due in part to bad editing of a publicized formula that had the percentages seriously compromised, as well as a bit of my own short-sightedness.
In any case, I queried folks on The Fresh Loaf for answers to my failures with this bread, getting great responses from a baker named Breadsong. According to Breadsong, one Teff-related challenge is that pre-gelatinization is a pre-requisite in stabilizing this almost-weeping grain. Because when added to doughs, it literally sweats, becoming difficult to handle. Once the pre-gelatinized flour is cooled, you add a white liquid levain. Then, it's a pretty straight forward formula, with bulk proof, and a 12 hour retarding and straight to the oven. The chocolaty flavor and crip crust are a winner.