Wash peas in cold running water. When water runs clear set aside to soak for 4 hours. Drain peas and put in sauce pan wit turmeric, salt, and green chilies. Add enough water to cover by 1 inch, and bring to a boil. Partly cover pan, reduce heat and simmer for 1 hour or until water has been absorbed and peas are tender but not mushy. Add more water if necessary Meanwhile, heat corn oil in a skillet. Add mustard seeds and cover pan. Saute for 2 minutes. Uncover pan, add onion and garlic, fry until golden. Stir in cayenne pepper and cook for 30 seconds. Add cooked spices to the peas. Stir cook for 2 minutes. Serve hot.