Preheat the oven to 200C/400F/Gas 6.
For the batter, whisk together all of the batter ingredients apart from the egg white. Leave to rest in the fridge for 20 minutes.
Slice the potatoes into your favourite chip shape. Boil for 10 minutes in a pan of salted water, or until the potatoes are soft to the point of a knife. Drain and transfer to an oven dish once completely dry. Season with salt and toss with the rapeseed oil. Bake for 25-30 minutes, or until golden-brown and crisp.
For the wasabi mashed peas, add the peas, butter and 300ml/10fl oz of water to a pan and cook over a moderate heat until the water has evaporated. Add the wasabi paste and mash the peas with a fork. Keep them warm until you're ready to serve.
To finish the batter, whisk the egg white in a bowl until stiff peaks form when the whisk is removed from the bowl. Fold it into the batter.
Half fill a pan with the sunflower oil and bring to a temperature of 180C/350F, which you can check using a sugar thermometer, or use a deep fat fryer set to the same temperature.
Flip the pieces of pollock in the batter and then carefully lower them into the hot oil, one at a time. Fry individually until golden-brown. Rest the fish on kitchen paper to remove excess oil and the serve with the chips and peas.