Place the bowl in which you will prepare the batter (preferably steel) and the whisk you will need to mix it in the freezer for 15 minutes. Clean the vegetables and cut them into not too thin sticks. Take a bowl larger than the one you will use for the batter and fill it with water and ice (remove the smaller bowl from the freezer and place it in the one with the ice). Put the egg yolk in and beat it for a few seconds, then add the iced sparkling water and the flour.
Stir for a few seconds and, if necessary, add a little more water, dip a few pieces of vegetables in it, then fry them in plenty of boiling oil for a couple of minutes.
When the vegetables are golden, drain them, add the salt and let them dry on a sheet of absorbent paper.
Serve hot.