Soak sago in plenty of water for 8 hours. Drain and set aside
Bring 5 cups of water to a boil in a big thick vessel. Add the drained sago and mix well. Simmer and cook for 10 minutes. The sago should get cooked well and the whole mixture should turn thick and glossy. You can also 2 teaspoons cumin seeds along with sago. While sago is cooking puree 2 large tomatoes along with 4 green chilies and set aside. Also grind 4 green chilies into a very smooth paste and set aside.
Once the mixture is thick and glossy remove from flame. Divide into two parts.
To one part add the tomato green chili mixture and mix well. Add lemon juice and mix well.
To the other part add green chili paste, salt and lemon juice. Mix well.
Now the mixture is ready. If you are going to sun dry this in cotton cloth, you can make vadams while the mixture is hot. If using plastic sheet wait for the mixture to get warm.
Spread the cloth or sheet on the terrace or patio. With small ladle take the vadam mixture and pour into small rounds. Sun dry for 3-4 days depending on the sunshine.
After 2 days, you can gently peel the vadams and keep in a tray, cover with a very thin cloth and sun dry.Once completely dried the vadam should be transparent and very light. Store dried sago vadam in airtight containers.
To serve, deep fry the required amount of javarisi vadam and serve with variety rice. You can also fire roast the sago vadam.