Sneha is an amazing place for a good Malayalam meal. Cant say how authentic it is, but seems to be the best place for that food in Mumbai. Do try the beef-fry with parotta and the fish thali. Its in Mahim, Mumbai, opposite Paradise Cinema. Ask for their desserts. Either the payasam or Ela Ada (which is a rice dosa/pancake kind of thing stuffed with coconut and jaggery/sugar mix, wrapped in a banana leaf and steamed. Awesome!