Suck the oysters, remove from shell and set aside.
Clean the domed oyster shells by scraping away the excess oyster from inside the shell and boiling them in water for 5 minutes, then transfer them into cold water.
Prepare the tempura batter by mixing the tempura flour with plain flour and the ice cold sparkling water.
Heat the sunflower oil in a pan.
Dip each oyster into the tempura batter, transfer to the pan and fry for 1-2 minutes.
Drain on kitchen towel.