In a chatti (earthern pot), add the vegetables, water, turmeric and salt and bring to boil. Cook till the vegetables are almost done.
Grind the coconut, yogurt if using, cumin and green chillies into a smooth paste. If not using yogurt, add a little water for grinding.
Add into the cooked vegetables and simmer for a few minutes till raw smell is gone. Do not boil.
Drizzle in the coconut oil and add the curry leaves. Switch off and allow to rest till serving.