1. Heat some oil in a pan to medium-high heat. Add the mustard seeds and the ginger and sauté for a couple of minutes. (I get the impression that you're supposed to cook mustard seeds until they "pop". I never quite manage to get mine to pop, but they seem tasty any way.) 2. Add the other spices and cook and stir for about 30 seconds. 3. Add the spinach and cook until it's done. 4. Turn off the heat and let the pan cool for a bit. Then fold in the yogurt.
It was quite tasty. Next time, I think I'll squeeze a bit of fresh lemon juice on it, or, if I can find some, substitute some sorrel for a bit of the spinach.