Combine the all-purpose flour, chickpea flour, diced onion, chopped parsley, and a pinch of salt in a large bowl until well mixed.
Add the cold water and mix to form a smooth, runny batter. Stir in the shrimp, making sure they are coated in the batter, then chill for 30 minutes for extra crispy fritters.
Pour a little less than an inch (2 centimeters) of olive oil into a large, shallow frying pan and set over medium-high heat until the oil reaches about 360°F (182°C).
Once the oil is heated, add tablespoons of the batter to the frying pan. The batter will expand and crisp up. Add enough fritters to fill the pan without them touching each other or the edges of the frying pan.
Fry until they are golden brown, turning them over halfway through to brown both sides.
Use tongs to remove the fritters from the pan, allowing excess oil to drip back into the pan. Gently put on a plate covered with paper towels and drain.
Season with salt and serve hot. Enjoy immediately!