Place all dill pickle mayonnaise ingredients in a bowl and mix to combine.
Place flour, cornflour, baking powder, sugar, salt and beer in a large bowl and whisk until just combined.
Peel and devein the prawns, leaving the tails intact or remove if desired.
Heat oil in a large saucepan over a medium heat until the temperature reaches 180ºC on a deep frying thermometer.
Dip the prawns in the batter and cook in batches for 1-2 minutes or until golden and cooked through. Drain on paper towel.
Spread mayonnaise over the base of the rolls and top with cooked prawns, lettuce and top of the roll. Serve with deli crisps and lemon.