Understanding how single-handedness of biological molecules came about has been of interest since Pasteur first separated mirror-image crystals of tartaric acid. Based on an experiment by Viedma, we have developed a method to convert a racemic mixture of chiral molecules to a single handedness by grinding a slurry of crystals under racemizing conditions. The handedness of the final state can be controlled in several ways, including the use of additives and circularly polairzed light. This provides a possible route for the origin of biological homochirality, but also a method that can be used in the pharmaceutical industry to produce chirally pure products.