1 medium russet potato or other starchy potato, peeled (about 8 ounces);
1⁄2 small red onion (about 2 ounces);
1⁄4 cup finely crushed saltine cracker crumbs;
1 large egg, lightly beaten;
1 teaspoon kosher salt, plus more to taste;
1⁄2 teaspoon ground black pepper;
Vegetable oil, for pan-frying.
Grate the zucchini, potato, and onion into long, thin strands on the large holes of a box grater or with the shredding disc of a food processor. Transfer into a colander and let drain for 3 minutes. Press the vegetables to extract as much liquid as possible and let drain for another 2 minutes. Pick up the vegetables in small handfuls, squeeze out as much liquid as possible and then transfer into a large bowl. Stir in the crackers, egg, salt, and pepper.
Pour oil to a depth of 1⁄4 inch into a large, heavy skillet (preferably cast-iron) and heat over medium-high heat until shimmering hot. Cover a wire rack with several layers of paper towels and keep near the stove to drain the cakes.
Working in batches of 4 or 5 cakes at a time, spoon rounded tablespoons of the vegetable mixture into the skillet and gently flatten the mound into a cake that is about 1⁄2-inch thick in the center. Cook the cakes until the edges are golden brown and they are set in the center, about 2 minutes, then flip them over. (If they bend in the center when you try to turn them, they’re not ready.) Brown the other side, about 2 minutes more. Transfer the cakes to the paper towels to drain. Add a little more oil to the skillet between batches if needed.
Sprinkle the hot cakes with a little more salt and serve hot.
What else works? You can replace the zucchini with summer squash or more potato. Do not omit the potato because its starch helps keep the cakes intact.