Wash the kerai and chop finely. Place a pressure pan or small pressure cooker over medium heat and add the kerai, cumin seeds and 1/4 cup of water. Pressure cook for one whistle and switch off. Wait five minutes and then open the cooker. Mash the kerai well and add salt to taste. Strain if any excess water If you like it more thick add the 1/2 cup of rice flour In a seperate pan, heat oil and add mustard seeds when hot. when it pops, add urad dal, red chilli and hing. When the dal turns brown add to kerai and stir well.