Injera is usually made from tiny, iron-rich teff seeds, which are ground into flour. Teff production is limited to certain middle elevations with adequate rainfall, and, as it is a low-yield crop, it is relatively expensive for the average household. As many farmers in the Ethiopian highlands grow their own subsistence grains, barley, corn, millet, rice, sorghum, or wheat flour are sometimes used to replace some or all of the teff content. Teff seeds are graded according to color, used to make different kinds of injera: nech (white), key or quey (red), and sergegna (mixed).
To make injera, teff flour is mixed with water. The fermentation process is triggered by adding ersho, a clear, yellow liquid that accumulates on the surface of fermenting teff flour batter and is collected from previous fermentations. The mixture is then allowed to ferment for an average of two to three days, giving it a mildly sour taste. The injera is baked into large, flat pancakes. The dough's viscosity allows it to be poured onto the baking surface, rather than rolled out, which is unusual for a yeast or sourdough bread. Traditionally, injera is made with just two ingredients – Eragrostis tef, also known as teff, an ancient grain from the highlands of Ethiopia, and water.