How to Make It
In a colander set over a bowl, toss the zucchini and weigh it down with a heavy can. Let the zucchini drain for at least 4 hours at room temperature or over or overnight in the refrigerator. Remove any excess liquid by squeezing handfuls of the zucchini in a kitchen towel.
Transfer the zucchini to a bowl and stir in the onion, Parmesan, flour, bread crumbs, mint and egg. Using slightly moistened hands, roll scant tablespoons of the batter into about 60 balls. Flatten the balls to form 1 1/2-inch patties about 1/3 inch thick and coat them lightly with flour.
Heat 1/2 inch of vegetable oil in a large skillet until shimmering. Working in batches, fry the patties over moderately high heat, turning once, until golden and crisp, about 1/ 1/2 minutes per side; lower the heat if necessary. Transfer to paper towels to drain and keep warm while you cook the remaining patties. Sprinkle with salt and serve.