Use a large cheese grater or mandoline to shred the zucchini until you have about 4 cups of shredded zucchini.
Wrap the zucchini in two layers of paper towels (or in cheesecloth) and squeeze until little-to-no liquid drips out.
Place the shredded zucchini in a large bowl with the 2 cups of panko, 1 egg, and 1 teaspoon of sea salt. Mix until combined, then use your hands to form patties about a half-inch thick and 3-4 inches wide.
Heat 5 tablespoons of vegetable oil over medium-high heat. Place 2-3 fritters into the shallow oil and fry until golden brown, about 2-3 minutes per side. Remove the fritters from the skillet and place on a paper towel to remove any excess oil.
While frying the fritters, in a small bowl stir together the mayonnaise and sriracha. Serve the fritters hot and enjoy!