Grate the zucchini on the large holes of a grater onto a clean kitchen towel. Sprinkle with the salt. Let stand while you prepare the other ingredients. Wring as much liquid out of the zucchini as possible, discarding liquid.
In a medium bowl, combine the zucchini, mint, dill, scallion, garlic, lemon zest, pepper and feta. Stir in the egg and flour and mix until well combined.
Heat enough canola oil in a pan over medium high heat to come halfway up the sides of the fritters. Form fritters, using 1/4 cup measure, and place gently into the hot oil. Fry, turning once, until the fritters are golden brown on each side, 4 to 6 minutes. Remove from the pan and drain on paper towels for a minute. Plate and garnish with a dollop of Greek yogurt, the picked dill and lemon zest.