In a small bowl, toss the shredded zucchini with ½ teaspoon kosher salt. Set aside for 10 minutes, then wrap in a clean kitchen towel or a triple layer of paper towels, and squeeze to release excess moisture. Set aside.
Place the butter in a large nonstick skillet (I used my Le Creuset 3½-quart braiser) set over medium-high heat. When the pan is hot, add the onion and garlic. Cook, stirring frequently, until the onion has softened, about 4 minutes. Stir in the corn and cook, stirring occasionally, for 3 minutes. Remove the pan from the heat.
In a small bowl, whisk together the cornmeal, flour, baking soda, kosher salt and pepper. In a second medium-sized bowl, whisk together the buttermilk and egg until well combined. Add the corn mixture and zucchini, and stir to combine. Add the cornmeal mixture, and gently mix just until everything comes together.
Add enough oil to the skillet to come to a depth of about ⅛-inch. Set the pan over medium heat. When the oil is hot, drop the batter into the pan using a 1/4 cup measure. Use the back of the measuring cup to flatten the batter into a round. Cook for about 3-4 minutes on each side, or until golden brown. Transfer to a paper towel-lined plate to drain and sprinkle with salt while still hot. Repeat with remaining batter (you may need to add additional oil as you get to the last few).
Notes
Notes:
The fritters can be made up to 2 hours ahead of time. Reheat them in a 375 degrees F oven on a wire rack set inside of a baking sheet.