Although larger than other mustard seeds, yellow mustard has less heat. It is the most commonly used variety and when ground into a powder, is hotter than the whole seed. Used for culinary purposes since prehistoric times, mustard seeds are still being used in much the same way; to make mustard, marinate meats and fish, and flavour and thicken sauces.
To make a powder, toast seeds in a pan for 20 seconds before grinding. To make a basic mustard, grind seeds and blend with water, vinegar, olive oil and salt.