Stone-ground brown mustard is a tangy, pungent condiment made from coarsely ground brown mustard seeds (Brassica juncea), vinegar, water, and salt. Stone grinding leaves some of the seeds partially intact, giving the mustard a textured consistency and robust flavor. Brown mustard seeds naturally contain glucosinolates, particularly sinigrin, which contribute to the characteristic pungency of mustard through their conversion to sulfur-containing isothiocyanates. Choose organic stone-ground mustard made with a short list of recognizable ingredients and without added sugars, artificial colors, or preservatives.