Slice peeled potatoes very finely using a mandoline or knife.
Soak potato slices in cold water for 30 minutes to remove starch.
Heat oil in a deep pan until it sizzles.
Dry potatoes thoroughly and deep-fry in batches until golden.
Drain chips on paper and season with salt.
Whisk egg whites in a bowl until stiff peaks form.
Mix egg yolks, flour, water, coconut, and herbs together.
Gently fold the egg whites into the flour mixture.
Season whiting fillets with salt, pepper, and lemon juice.
Coat fillets in flour, then dip into the batter.
Fry battered fish in hot oil for 8 minutes until golden.
Combine mayonnaise, capers, gherkins, horseradish, and parsley for the sauce.
Serve fish with chips and a dollop of tartare sauce.