Fill a large bowl with ice water and set aside. Fill a large Dutch oven with water and bring it to a boil over high heat. Add the cauliflower and cook until just tender, about 5 minutes. Drain the cauliflower and transfer it to the ice bath to cool, about 2 minutes. Use a slotted spoon to transfer the cauliflower to a paper towel-lined baking sheet, and pat all over with paper towels to dry. Rinse and thoroughly dry the Dutch oven and return it to the stove.
In a medium bowl, beat the eggs until combined, and set aside. Into the empty Dutch oven, pour the oil to a depth of 2 inches, attach a deep-fry thermometer, and turn the heat to medium-high. While the oil is preheating, in a shallow baking dish, whisk together the flour, lemon zest, cayenne, salt, turmeric, and black pepper to taste.
Line a baking sheet with paper towels. When the thermometer reads 350°F, dredge a few cauliflower florets in the flour mixture, shaking off any excess. Transfer to the egg to coat, then return to the flour mixture to dredge again. Fry, flipping occasionally, until crisp and golden, about 45 seconds. Using a slotted spoon, transfer the cauliflower to the baking sheet and season with salt and black pepper while hot. Working in batches, repeat with the remaining cauliflower.
To serve, transfer the cauliflower to a platter, sprinkle with the parsley, and serve with lemon wedges, for squeezing.