Place the white pepper and Sichuan pepper in a mortar and pestle and grind to a powder.
Add the salt and mix to combine then set aside.
Preheat oil in a large saucepan or wok to 190ºC.
Place the cornflour and half the salt and pepper mix in a bowl and mix to combine.
Peel prawns leaving tail intact.
Add to mix and toss to coat. Shake off any excess flour and cook in batches for 2‐3 minutes or until golden and crisp.
Drain on kitchen paper and serve with fresh lemon and extra salt and pepper mix.