Not sure how to post here, but Julie Sahni has a good recipe for hot and sour garlic-braised eggplant that uses a cup of mustard oil. She gets you to heat it until smoking and then let it cool before proceeding, to get rid of the bitterness. It's in "Classic Indian Vegetarian and Grain Cooking". Our go to recipe for red lentils is in that book too, Bengal Red Lentils with Spices.