Take all the ingredients listed under "for grinding" as per the measurement.
Transfer all the above ingredients along with coconut into a mixe jar or blender. And make a fine paste using required water. Set it aside.
Take 2 tbsp of oil in a wok or frying pan and heat it. Now prepare tempering using mustard seeds, urad dal, red chili and curry leaves.
Add in chopped onions and fry until soft.
Add in chopped tomatoes and give a quick mix.
Add in turmeric powder, salt and little water. Adding all these help in fast cooking.
Add in turmeric powder, salt and little water and fry until tomatoes are soft.
Add in ground masala and required water.
Adjust salt level and mix well. Please note you have already added some salt. The sagu shall have thick gravy consistency. Bring it to boil and continue boiling for 5 minutes under low flame. Serve it with set dosa or poori or chapathi.