Teff is a kind of millet with grains about the size of an ordinary pin-head, of which is made the bread commonly eaten.
Dealers weigh out teff, barley and finger millet which form the staple diet.
Teff flour has a slightly sour taste which may or may not work well with your recipe.
Look for amaranth, teff, buckwheat or even hemp flour.
For flours and thickening agents, gluten-free flours such as corn starch, teff flour, and coconut flour make good substitutions.