Detach the tails of the langoustines and shell them, leaving the last ring and the tail. Wash and pat dry the celery leaves.
Prepare the dough:in a bowl, pour 17 cl of very cold water, add the egg yolk and whisk quickly, incorporate the flour and salt without stopping whisking.
Finely chop 2 celery leaves, add them to the dough.
Heat the oil in a saucepan or frying pan. When it is hot, pass the langoustines lightly in the flour, dip them in the batter and immerse them in the frying pan. Let it cook for 2 to 3 minutes, turning it over. Cook all the langoustines, then in the same way, but just for a minute, the celery leaves.
Remove the donuts with a slotted spoon, place them on a paper towel, then in the serving dish and serve immediately.
