In a pressure cooker, add the tomatoes, green chilli, one sprig of curry leaves and turmeric powder and cook for 2 whistles with ½ cup water. Or you could use a deep bottom pan, add the above and cook till the tomatoes turn mushy.
Blend grated coconut, cumin seeds and garlic cloves into a fine paste.
Once the tomatoes are cooked, scoop out the tomato bits and blend; this helps the curry to have a smoother consistency. You can skip this step if you like the tomato bits in your curry.
Return to pan, add the coconut paste, sugar and bring to boil. Season with salt and cook on medium heat for 5-6 minutes or till the curry has thickened.
Make a tempering or tadka using coconut oil, mustard seeds, curry leaves and dry red chilli.
Pour this over the curry and serve hot with steamed white rice.