Its just an oil, you would think. Whats so special about an oil made from seeds? Well, mustard oil is not just like any other oil you use in your cooking. It is a true superhero. Mustard oil is extracted from the seeds of the mustard plant. It has culinary as well as therapeutic uses. Here are some quick facts about mustard oil. The first method is to press the mustard seeds to get vegetable oil. The second method is to grind the seeds, mix them with water, and then extract the oil by distillation. This results in mustard oil that is lower in fat content.