Rai Kuria/Split Mustard Seeds- Rai (pronounced raa-ee) or mustard seeds are very common in Indian cooking. These are usually used as a tempering/tadka ingredient. The split mustard seeds (typically yellow in color) are often used to make Indian-style achaar (pickles). These have a pungent, slightly bitter-ish taste. Since we are keeping the ingredient list in this recipe to a very few, the addition of this is a must. It adds a few flavors on its own to make the fish fry exciting.