Heat the oil in a large saucepan over a moderate heat then add the onions and cook until soft and translucent, about 8-10 minutes, Add the garlic, chilli, sugar and all the spices apart from the tamarind. Fry for 2-3 minutes more.
Meanwhile put the eggs into a saucepan and cover with cold water. Cover the pan and bring to the boil. As soon as the water begins to boil time the eggs for 6 minutes. Remove from the heat, cover with cold water then set aside until cool enough to peel and halve.
Add the thawed spinach, tamarind and the coconut milk to the onion mix and heat through. Add the eggs and season well with salt and pepper.