Place grated zucchini in a clean kitchen towel or cheesecloth and squeeze firmly to remove excess moisture. For best results, remove at least 1/2 cup of liquid from your grated zucchini.
Transfer the drained zucchini to a large mixing bowl. Add chopped onion, beaten eggs, flour, Parmesan cheese, garlic powder, oregano, salt, and pepper. Mix thoroughly until all ingredients are evenly incorporated.
Using a 1/4 cup measuring cup, scoop the mixture and form into patties approximately 3 inches in diameter and 1/2 inch thick. Slightly flatten each patty with your palm for even cooking.
Heat olive oil in a large non-stick skillet over medium heat. When the oil shimmers (but doesn't smoke), carefully add the patties, leaving enough space between each one.
Cook for 3-4 minutes per side until golden brown and crispy. Avoid overcrowding the pan, as this can lead to steaming instead of crisping.
Transfer cooked patties to a paper towel-lined plate to absorb excess oil. Serve immediately while hot and crispy for the best texture and flavor experience.