Add the oil to a big pot and heat it up until hot. Add the onions and stir-fry until aromatic before adding the curry powder. Do a few quick stirs until you smell the aroma, then add the chicken, stir to combine well, for about 1 minute. Add the water into the pot and bring it to boil. Lower the heat and add the tomatoes, potatoes and eggs. Cover the pot and let simmer for about 30-45 minutes, or until chicken becomes tender. Add the coconut milk and salt to taste and simmer for another 5 minutes or so. Dish out and serve immediately with steamed rice.