Grate the zucchini on the large holes of a box grater into a large bowl.
Scoop the zucchini into a fine mesh sieve set over the bowl or the sink and sprinkle with the salt. Toss to combine. Let the zucchini sit for 15 minutes.
Use the back of a spoon to firmly press the zucchini against the sieve to remove as much water as possible. Alternatively, scoop the zucchini into a kitchen towel and twist both ends to squeeze out the water.
Discard the zucchini liquid and return the grated and drained zucchini to the large bowl.
Add the egg, flour, chives, all-purpose seasoning, lemon zest, and baking powder and mix gently to combine.
Spray a baking sheet with cooking spray or slick with oil. Using wet hands, gently shape the zucchini mixture into 2-tablespoon sized patties and place on the baking sheet. You should get about 6 patties.
Heat the Blackstone or other griddle to medium and coat with cooking spray or slick with oil.
Use a metal spatula to gently transfer the zucchini fritters from the baking sheet to the griddle. Cook, flipping once, until golden brown and fluffy, about 5 minutes per side.
Serve immediately, with sour cream for dipping, if desired.