In a clean mixing bowl, whisk together the flour, cornflour and enough sparkling water to make a smooth batter the consistency of double cream.
Heat the vegetable oil in a heavy-based saucepan until a breadcrumb sizzles gently when added to the pan. (CAUTION: hot oil can be dangerous! Do not leave unattended.)
Dip the chicken and spring onions in the batter to coat completely, then carefully lower into the hot oil.
Deep fry for 3-4 minutes, or until the chicken is cooked and the batter is golden-brown and crisp.
Carefully lift out with a slotted spoon and drain on kitchen paper. Season with salt and freshly ground black pepper. Serve immediately.
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