Wgriffin, I think that popping the mustard seeds is the trick. Heat the oil hot but not to start smoking & burn. I do this by closely watching the oil heat up & when I think it’s hot but not too hot, I put just a few mustard seeds in. When they start to pop, I add the rest of the mustard seeds. That way I can monitor the heat & know that the oil is hot enough so they will all pop. One time I cooked the seeds very hot but not too hot & the soup had a wonderful nutty flavor. I would personally try to do this again.
DO NOT add the spices until your seeds are all popping & then you may want to turn your spices heat down a bit, but still simmering your ghee.