Shred the zucchini and place in a sieve over a large bowl. Sprinkle with 1/2 tsp. salt and let stand for 10 minutes.
After 10 minutes squeeze out as much liquid from the zucchini as possible.
In a new large bowl, add the flour and eggs and whisk.
Add the zucchini, green onions, onions, garlic and black pepper and gently fold to combine.
Heat the oil in a large skillet over medium high heat.
Scoop 1 Tablespoon of batter and place in hot oil. Press down gently to flatten. Repeat until the skillet is full, but the batter isn't touching.
Cook about 2-3 minutes per side, until the outside is golden brown.
Repeat the above 2 steps until all the fritters have been fried.
Add a small pinch of salt and sour cream to each cake and serve immediately.