If you cannot get your hands on a Shil Nora, there are other options available for making a paste. A regular grinder will do the job, although it may take longer. Electric grinders designed for making pastes are also available. Soak mustard seeds in warm water for 15 minutes before making the paste. For Posto or Khuskhus, dry grind first and then add water to make a thick paste. Add a pinch of salt in both cases.