Start out by boiling potatoes until just tender, then cut them into 2-inch pieces. Heat oil in a pan and cook mustard seeds until they start to pop. Add asafoetida, fenugreek seeds, and curry leaves, and cook another minute before adding garlic, chiles, and onion. Once everything is golden, add the potatoes, peas, remaining spices, and some water and bring to a boil. Over low heat, continue to cook until potatoes are fully cooked and slightly dry. Serve with cilantro.