This dish is inspired by the Creten meze dish Kolokitho Keftedes
Mix zucchini and salt in strainer; set weighted plate on top; let drain for 30 minutes. Transfer zucchini to a cheese cloth or clean dishtowel (flour cloth works well here); squeeze out liquid. Mix zucchini, parsley, cheese, bread crumbs, onions, and egg in bowl. Season with pepper and cayenne; divide mixture into 12 balls. Press balls into ¾"-thick patties. Pour oil into 4-qt. pot to a depth of 2"; heat over medium-high heat until deep-fry thermometer reads 315°. Working in 2 batches, fry patties until browned and crisp, 5-6 minutes. Using slotted spoon, transfer fritters to paper towels.