For the French-style peas, place the peas, onion and white wine into a small saucepan and cover with a little boiling water. Simmer over a low heat for 5-6 minutes, or until the onion and peas are tender and the liquid has reduced by half.
Mix the butter and flour together until it forms a paste (this is called a roux), then stir into the pan with the cooked peas to thicken the sauce. Stir in the chopped mint.
For the prawn 'scratchings', place the flour, chilli flakes, chives, salt and freshly ground black pepper into a large bowl and then gradually whisk in the cold sparkling water until the mixture is smooth and reaches the consistency of double cream. (You may not need all of the water).
Pour the vegetable oil into a saucepan and heat until a small cube of bread dropped in sizzles and turns golden in 30 seconds. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Dip the chopped prawn pieces into the batter and then carefully lower into the hot oil. Fry for 2-3 minutes, or until golden-brown and crisp. Remove with a slotted spoon and drain on kitchen paper.
To serve, spoon the peas onto a serving plate and top with the crisp prawn 'scratchings'. Garnish with the mint sprigs and serve.