Prepare your baby squid by patting it dry with a kitchen paper to soak up any excess moisture, as if it is wet when it goes into the oil it will spit everywhere which is dangerous. Take particular care with the tentacles if you are using them, as they are good at harbouring moisture. If there is any membrane/film left on the tube, peel it off first.
Slice the tube of the baby squid into two or three rings, each around ¾ inch thick.
Make your tempura batter by quickly whisking ice-cold sparkling water into the tempura flour. Add the lemon zest and season with salt and pepper but do not over stir the batter as gluten will start to form, which in turn will make the popcorn calamari chewy rather than crispy.
Add the baby squid rings to the tempura batter and lightly stir through.
Deep fry the popcorn calamari at 180 degrees Celsius / 360 Fahrenheit. If you do not have a deep fat fryer it is fine to use a deep saucepan, just make sure to use a thermometer to ensure you have the right temperature (and make sure it has a big enough range, a sugar thermometer is best).
Use a pair of tweezers or small metal cooking tongs to pick the popcorn calamari out of the bowl of batter to ensure they separate from one another and do not end up as one enormous clump.
Add the battered calamari popcorn to the hot cooking oil carefully and keep an eye on the oil temperature. Adding it all at once seems tempting but this can bring down the temperature too much, so frying the popcorn calamari in small batches is often a good idea especially if you using a saucepan on a stove.
The popcorn calamari will not take long to cook, when they reach a light golden brown colour they are ready.
Using a metal slotted spoon, remove the cooked calamari popcorn to a plate covered in kitchen paper to soak up any excess cooking oil.
Serve your popcorn calamari in a warmed bowl topped with some torn fresh basil and a squeeze of fresh lemon juice. And enjoy!