Wash, peel and cut the beetroot into small cubes and set aside.
Heat the oil on a low heat and fry the mustard seeds, ajwain, cumin seeds and coriander seeds. When the mustard seeds begin to splutter, add the curry leaves, fenugreek leaves, chopped onion, chillies, garlic and ginger and stir. Lower the temperature and add the mango powder.
Add the beetroot cubes. Stir well and then add the salt. Add the water, cover the pan with a lid and cook the beetroot for 10 mins on a low heat.
Once the beetroot is cooked, add the coconut milk and cook for a further 10 mins without the lid on to reduce the coconut milk down. Remove from the heat and add the chopped fresh coriander. Serve.