Pressure cook tomatoes with water to give one whistle. Keep on low flame for 5-7 minutes. Remove from fire.
After the pressure drops, strain the tomato juice. Mash well to extract all the juice. Keep aside.
Grate 1 cup of fresh coconut. Blend it with its own water in a mixer. If fresh coconut is not available, blend 1 cup dessicated coconut with 2 cups hot water in a mixer. Strain to extract milk. Put the unstrained coconut again in the blender with more hot water and churn again. Strain again. Repeat with more water if desired to get 4 1/2 cups coconut milk in all.
Add besan to the coconut milk and blend well in the mixer. Keep aside.
Heat the ghee in a pan and add Jeera. After it splutters, add curry leaves, green chillies, tomato juice, coconut milk and sugar.
Add salt to taste and cook for 4-5 minutes. Add lemon juice to taste.
Garnish with coriander leaves and a few grains of boiled rice. Serve hot.