Step 1

Heat the oven to 180°C/160°C fan/gas Bring a pan of salted water to the boil. Blanch the fennel and potato slices in the water for 3 minutes, remove with a slotted spoon and transfer to a shallow roasting tin large enough to hold the fish comfortably. Add the onion, chilli flakes, fennel seeds and a generous drizzle of oil, then toss everything together to coat. Roast for 10 minutes, turning halfway, until lightly golden (see Make Ahead).

Step 2

Remove the tray from the oven, pour over 125ml white wine, then add most of the lemon wedges and half the tarragon. Season well and toss together.

Step 3

Rinse the turbot and pat dry with kitchen paper, then set on top of the vegetables and drizzle with some more olive oil. Season well with salt and pepper and roast for 20 minutes.

Step 4

Add the clams and the remaining white wine to the tin, then cook for a further 10 minutes until the flesh of the fish is just cooked through and starts to come away from the bone, and the clams are open and cooked (discard any that remain unopened).

Step 5

Scatter over the chopped parsley and remaining tarragon, then squeeze over the juice from the remaining lemon wedges to serve.