Offering Food or Naivedyam/Prasadam is integral part of Vaishnava lifestyle. Majority of Vaishnavas follow Pancharatra Agama shastras, therefore I assume Naivedyam procedure is described in those texts.
So the question becomes :
What is the method(from Pancharatra texts) to offer Naivedyam to Shriman Narayana.
If there is a difference in Sri Vaishnava Naivedya procedure them please mention that in your answer.