The principal grains are teff, wheat, barley, corn, sorghum, and millet. In Ethiopia, teff flour is fermented to make injera. Khat, ensete, noog, teff and finger millet were also domesticated in the Ethiopian highlands. The cultivated crops are (endemic) teff, maize, sorghum, beans and vegetables. To make injera, teff flour is mixed with water. It is brewed from various grains, typically teff and sorghum. Injera is usually made from tiny, iron-rich teff seeds, which are ground into flour. Regional staples include the plants rye, soybeans, barley, oats, and teff. Gluten-free sandwich bread may be prepared using gluten-free flour, teff flour, and other ingredients. The fiber content in teff is also higher than in most other cereals. It is cultivated for its edible seeds, also known as teff. Lack of mechanization is a barrier to potential increases in teff exports. In 2016, Ethiopia grew more than 90 percent of the world's teff. There are symbolic value differences with types of teff as well. The major challenges in teff production are its low yield and high susceptibility to lodging.