Shred the potatoes and place in a colander. Sprinkle with some salt and toss to combine. Let stand to drain for 10-15 minutes.
Preheat waffle iron to a little less that high.
Squeeze remaining liquid from the potatoes and place potatoes in a medium bowl. Beat eggs in a small bowl and add to the potatoes, together with the flour, baking powder and a bit of salt and freshly ground peppers. Stir to combine. Add sour cream, melted butter, cheddar cheese and green onion. Stir to combine.
Spray waffle iron with cooking spray. Add 1/3 of the batter (if making 3) to the centre of the waffle iron and spread out towards the edges a bit. You don't need or want to cover the entire surface. Cook waffles 5-6 minutes, or until cooked through and very golden. Remove to a cooling rack (or to a baking sheet to pop into a 300F oven if you want to keep them warm while you make more.)
When waffles are cooked, heat oil in a skillet over high heat. When very hot, break eggs into oil and cook until edges of egg are crispy and browned and whites are set, about 1 minute. Remove pan from heat and let stand another 30 seconds. Place egg on top of waffles and garnish with additional diced green onion.