Prepare the vegetables: Rinse and dry the vegetables thoroughly. If necessary, cut larger pieces into bite-sized chunks so that they are all roughly the same size. This ensures they cook evenly in the oil.
Make the tempura batter: Whisk the flour, salt and baking powder together in a bowl. Add the cold sparkling water a little at a time and stir briefly until the batter comes together. It’s fine if it’s a bit lumpy – this will make it extra crispy when fried. Place the bowl in the fridge until the oil is ready.
Heat the oil: Pour the oil into a deep saucepan or a deep-fryer. Heat it slowly to approx. 180°C. If you don’t have a thermometer, you can test it with a wooden spoon: if the oil bubbles vigorously around the handle, it’s ready.
Fry the vegetables: Dip a handful of vegetables at a time into the tempura batter, ensuring they are evenly coated. Use tongs or a slotted spoon to carefully lower them directly into the hot oil. Fry in small batches so the oil doesn’t cool down too much.
Fry until crisp and lightly golden: Let the vegetables fry for approx. 4–5 minutes, until they are completely crisp and only lightly golden. Turn them occasionally so they brown evenly.
Drain and serve immediately: Remove the fried vegetables with a slotted spoon and place them in a sieve or on kitchen paper to allow excess oil to drain off. Sprinkle immediately with a little fine salt and serve piping hot with the aromatic vinegar for dipping.
Mix everything together and season to taste; leave it to stand for 30 minutes before serving.
