For serving; sour cream or plain Greek yogurt, tzatziki sauce, or marinara sauce
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.
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.
Line a plate or platter with paper towels and set aside.
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.
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.
Transfer to lined plate and cover with foil to keep warm while you repeat with remaining batter.
Serve warm with a dollop of sour cream or plain Greek yogurt, tzatziki sauce, or dunk the fritters in marinara sauce.
You can use a food processor or box grater to grate the zucchini. Store leftover fritters in the fridge for up to 1 week. You can also freeze the fritters for up to 2 months.