Step 1

Lightly whisk the egg, arrowroot, turmeric, 2 tsp lemon zest, a pinch of salt and 1/2 cup (125ml) iced water in a bowl. Set aside.

Step 2

To make the yoghurt tartar sauce, combine the yoghurt, mayonnaise, lemon juice, cornichons, dill and capers in a bowl and season. Set aside.

Step 3

Cook the couscous according to packet instructions, then fluff with a fork. Add the parsley, onion and remaining lemon zest, then season and stir to combine. Cover and keep warm.

Step 4

Half-fill a large saucepan with the oil and heat to 160°C (a cube of bread will turn golden in 45 seconds when the oil is hot enough). Season the fish, then dip in the batter, shaking off any excess. Deep-fry for 2-4 minutes until golden and cooked through. Drain on paper towel.

Step 5

Divide lemon couscous among serving plates and top with fish. Serve with the sauce, extra dill and lemon wedges.