Sessile oak

Cooked seeds can be dried and ground into a powder, which can be used as a thickening agent in stews or mixed with grain to make bread. The seeds contain bitter tannins, which can be removed by thoroughly washing the seeds in running water, although this can also wash away many minerals. The whole seeds can be used or dried and ground into powder. To properly leach the seeds, they can be soaked for several days to weeks, with one method being to pack them in a cloth bag and place it in a stream to speed up the process. A simple taste test can indicate when the tannins have been washed out. Traditionally, the seeds were buried in moist soil to overwinter, and in the spring, the germinating seeds were dug up. By that time, most of the astringent properties would have been lost. Roasted seeds can serve as a coffee substitute.