- Preheat pan and Roast walnuts for 6-7 minutes. Grind 1 cup of roasted walnuts with 4 cups water in a blender until you get a smooth liquid. Pour the liquid into a pan and bring it to a boil. Now add liquid jaggery and stir. Dissolve between 1-2 tbsp of rice flour in about 1/8 cup of water until you get a smooth paste. Add it to the boiling walnut payasam. In about 30 seconds, when the liquid thickens, switch off the heat. Serve.