Pour the water into a large saucepan with a generous pinch of salt. Whisk in the flour vigorously until it is well incorporated, to form a rather thin batter.

Turn on the heat and bring the batter to a simmer, whisking all the while to prevent lumping. As soon as it comes up to temperature, it will thicken very quickly. Once it is quite dense, take it off the heat. Mix in the minced parsley and ground black pepper if using.

While it is still hot, transfer the cooked batter to a flat, non-pourous surface (a cookie sheet, for example) which you have greased well with some olive oil. Using a flat spatula, spread the batter out very thin, about 3mm (1/8 in). Let the batter cool completely; it will solidify as it cools. Cut the batter into small squares or rectangles about 5cm (2 in) and gingerly lift the pieces off the surface with the spatula.

Deep fry the pieces in hot (190C/375F) oil until they are golden brown, working in batches if need be to avoid crowding.  They should puff up a bit as they fry. Drain them on paper towels as they are done. 

Serve your panelle right away, sprinkled with salt. If you like, have some lemon wedges on the side for those who like their panelle sprinkled with some lemon juice.