In a cooking pan or pressure cooker, dump the onions, tomato, turmeric, chili and coriander powder, salt and water. Pressure cook for 2 whistles. Remove and let it cool.
If not using a pressure cooker, you can over a Dutch Oven or Saucepan and cook covered for 30-45 minutes on low flame.
Heat oil in a cast-iron pan with oil. Once hot, pour the onion-tomato mixture and peas. Cook for 30-45 minutes until all the water dries and the mixture gets a beautiful roasted texture and color. It needs to form a gorgeous black base.
Serve hot with chapatti/roti and cucumber.