Use orange or yellow sweet potatoes. Don't use Asian white sweet potatoes - they're too dry for this recipe! I use Bob's Red Mill Teff Flour. The nutrition label says 1/4 cup equals 40 grams. That means 1 cup is 160 grams. However, the King Arthur Flour website says 1 cup of teff flour weighs only 135 grams! The only thing I can think of to explain the discrepancy is that the heavier measurement was achieved with unsifted flour using the scoop and sweet method, and the lighter measurement came from sifted flour. So please measure your teff flour by weight if possible. If you don't have a scale, do not sift your flour for this recipe. Simply dip your measuring cup into the bag of teff flour (or pour the flour into the cup) and level the top with the back of a butter knife.