In a heavy pot, heat the ghee over a medium heat. Add the mustard seeds; it should be just hot enough for the seeds to crackle, but not burn. Stir in ginger, garlic, cinnamon, green and red chillies and curry leaves. Cook, stirring frequently, for approx 30 seconds.
If rice is cold, add rice to pot with a little water, and cover. The steam will separate the rice. When rice is warm, or if adding warm rice, stir rice with spices. Reduce heat, mix in yogurt, and heat through.