Manioc flour is made from the tuberous root of the Manihot esculenta plant, which is native to Central and Southern America. This woody shrub is more commonly known as manioc, cassava, or yucca, and in addition to being the source of this flour, it is also used to produce tapioca and whole in recipes in which it may be fried, steamed, or stewed. It has been used by Native Americans for centuries, and many Latin American cultures call for it in traditional recipes.
For people who are not making Latin American food, the primary reason to use manioc flour is that it is gluten free. It can be used in recipes for cakes, cookies, and other dishes, either on its own or in combination with other gluten-free flours. The flour has a coarse, mealy texture and a nutty flavor with a faint hint of acidity that can be quite distinctive.
The best source for this flour is a Latin American market. It may also be labeled tapioca flour, polvilho, yucca flour, or cassava flour, and in some regions, people know it better as farinha de mandioca. The flour is made by grating the raw tuber, allowing the pieces to dry, and then grinding them. Some cassava plants have dangerous substances in their roots that require people to soak the roots before and after grating, to leach these substances out; manioc flour is perfectly safe to use as-is, since it has been treated to remove any toxins as part of the process used to turn it into flour.
In Latin American cuisine, the flour is often used as a breading for fried food and as a constituent in cakes and breads. It may be used alone or mixed with other ingredients, depending on the taste of the cook, so people who are traveling in Latin America should not assume that something made with this flour is inherently gluten free.
Cooks who have never worked with manioc flour before may want to use recipes that are specifically designed for this flour to allow them to grow accustomed to it. Once a cook is familiar with the way in which the flour behaves as it is used, he can experiment with substitutions and recipe alterations to suit his specific needs. Like all flours, manioc can go bad if stored improperly; cooks should keep it in a sealed container in a cool dry place and try to use it within six months. The flour can also be frozen to last longer.