In a mixing bowl, combine sour cream, ranch packet, Rotel, corn and shredded cheddar cheese. Stir to combine well. Garnish with extra cheese and chopped green onion.
Refrigerate until ready to serve, best to refrigerate for at least an hour to thicken up the dip. Can be served right away, however.
Store extra fiesta corn dip in an airtight container for up to 3 days.