The ingredients are blended and usually warmed in a double boiler to thicken. Homemade mustards can be strong at first. They mellow if left at room temperature for a few hours. They last a long time when refrigerated. They make great gifts.
Commercial mustards are often mixed with flour to temper the heat and are colored with turmeric.
Homemade mustards retain the dull yellow of the seed and are far superior in flavor and aroma. Once you've made your own, you'll never look back. No special equipment is required for mustard making. A food processor, food mill, or blender will do for grinding mustard seeds. Make sure the mustard powder you use is fresh.