The recipe doesn't specify - how many green onions - and are they chopped? thank you.

Chopped and what he said!

Just go based on your own personal taste preference really. Don't be afraid to improvise on recipes where the ingredient count/quantity might be a bit vague or if you prefer the taste/quantity of something more than another. Go with what you like in terms of taste/texture/etc.....in this case green onions!