Chop two of the onions to fine pieces.
Grind the third onion and garlic to a fine paste.
Saute the finely chopped onions till light golden brown. Then add the onion-garlic paste and saute for two minutes.
Now, add the tomato puree, required quantity of salt and chilli powder and mix well. Add some water if required, to get the right consistency.
Let it boil for 5 minutes.
Garnish with finely chopped coriander leaves.