Place grated zucchini in a colander in the sink or over a bowl. Sprinkle with kosher salt and toss well. Let sit for 10 minutes. Use a spatula or spoon to press down on the zucchini to push out the liquid. Transfer the zucchini to a clean dish towel, paper towels, or cheese cloth and squeeze out excess liquid. Don’t skip this step. You want to remove as much moisture as possible.: The grated zucchini will release its liquid promptly, and you should notice droplets forming around the strands, which is normal and expected. Letting it sit with the kosher salt draws out moisture, and you will feel the zucchini soften as the liquid separates. This step matters because moisture is the enemy of crispness, and squeezing the zucchini later prevents watery batter. A common mistake is skimming this step, which results in fritters that fall apart or steam instead of browning properly.
In a large bowl, combine the grated zucchini, flour, panko, Parmesan cheese, scallions, garlic, egg, lemon zest, and pinch of crushed red pepper flakes. Add a little salt and black pepper, to taste.: When you mix these components you should sense a cohesive mass forming, with the Parmesan cheese and panko absorbing any remaining dampness. The aroma of garlic and lemon zest will become noticeable, teasing the final flavors. This combination creates the ideal balance between binder and texture. If you add too much flour here, the fritters will be dense, so keep measurements accurate.
Line a plate or platter with paper towels and set aside.: The paper towels will be your landing pad for cooked fritters, and you should see them collect tiny beads of oil as you transfer golden rounds from the skillet. This keeps the fritters crisp rather than oily. If you skip this rest, oil will pool and the fritters can become soggy; always prepare your draining station beforehand.
In a large cast iron skillet or nonstick skillet, heat the olive oil over medium high heat. When the oil is hot and shimmering, drop about 1/4 cup of the fritter batter into the pan. Lightly flatten with a spatula. You can make 3 to 4 fritters at a time, just make sure they aren’t touching.: Heat the olive oil until it is shimmering and fragrant, but not smoking, which is the cue to begin frying. You will hear a lively sizzle when the batter hits the pan, a satisfying sound that means the exterior is caramelizing. The right oil temperature ensures even browning and minimal oil absorption. Frying at too low a temperature causes greasy fritters, while too hot will burn the exterior before the center cooks through.
Cook for 3 minutes until deep golden brown. If the fritters are browning too quickly, you can turn down the heat a little. Flip and cook the other side for 3 minutes until deep golden brown. You might need to add a little more oil as you go.: As you drop the batter, flatten lightly with a spatula so the fritters cook evenly and develop a broad golden surface. You will see edges set quickly and small bubbles appear as moisture escapes. Keep fritters separated so they do not steam each other. A misstep here is overcrowding the pan, which lowers the oil temperature and prevents proper browning.
Transfer to lined plate and cover with foil to keep warm while you repeat with remaining batter.: During these minutes watch for a deep golden hue forming along the edges and underside, and listen to the steady sizzle indicating proper heat. The smell will turn toasty and nutty as the Parmesan cheese begins to brown, which adds flavor. If you notice rapid darkening, reduce the heat slightly to allow the center to catch up without burning the outside. Flipping too early can cause the fritter to tear, so let the first side set firmly.
Serve warm with a dollop of sour cream or plain Greek yogurt, tzatziki sauce, or dunk the fritters in marinara sauce.: After flipping, press gently with the spatula just once to ensure contact with the pan and even browning. The second side often cooks faster, and you will hear a slightly different, crisper sizzle as excess moisture has mostly cooked off. If the fritters need more time, adjust the heat rather than extending at the wrong temperature. A typical error is flipping multiple times, which can break the crust and cause sogginess.
You might need to add a little more oil as you go: As you cook multiple batches the skillet will lose some oil to absorption and evaporation, and adding a splash maintains the ideal frying surface so the next set browns correctly. The oil should always coat the pan lightly for even conduction. Add too much oil and the fritters will sit in fat instead of crisping, so replenish modestly.
Transfer to lined plate and cover with foil to keep warm while you repeat with remaining batter: The plate will collect a faint sheen of oil while the foil preserves warmth and prevents drying. You want to serve the fritters hot, so working in batches and covering them briefly helps maintain texture. Avoid stacking too many fritters when covered, because trapped steam can soften the crust.
Serve warm with a dollop of sour cream or plain Greek yogurt, tzatziki sauce, or dunk the fritters in marinara sauce: Serving immediately provides the best contrast between the crisp exterior and tender interior, and the sauces add cooling or tangy accents. Each sauce shifts the character slightly, for instance tzatziki sauce adds herbaceous brightness while marinara sauce gives a comforting, tomato forward pairing. Reheating later will still be tasty, but expect some loss of crispness.