Place the zucchini in a colander. Sprinkle with salt, and set aside for 30 mins.
Squeeze as much of the liquid as possible from the zucchini with your hands.
In a medium skillet, cook the onions in the butter over medium-high heat about 3 mins or until tender, stirring occaisionally.
Transfer the zucchini and onions to a large bowl.
Stir in the eggs, flour, and pepper.
Pour the oil into a medium skillet to a depth of 1/8 inch. Heat over medium high heat.
Drop slightly rounded tablespoons of the batter into the hot oil and flatten to a 3 inch diameter with the back of a spoon.
Cook the pancakes over medium high heat until golden, turning once (2-3 minutes on each side) Remove and drain on paper towels. Add more oil to the skillet, if needed, and repeat until all of the batter is used.