For the plaice, score the skin side of the plaice lightly. Season with salt and freshly ground black pepper. Carefully roll up each fillet, skin-side up, into paupiettes (pinwheels).
Place into a steamer and cook for 4-5 minutes, or until just cooked through.
Blend the coriander leaves and olive oil in a food processor to a fine purée. Pass through a fine sieve into a bowl.
For the cauliflower purée, cook the cauliflower florets in boiling water for 4-5 minutes, or until just tender, and drain.
Blend with the butter and cream in a food processerto a purée. Season with salt and freshly ground black pepper.
For the soused turnip, heat the vinegar, sugar and salt in a saucepan until simmering. Pour the mixture over the sliced turnip and mix until well combined. Set aside to marinate for five minutes (or up to 24 hours). Drain the turnip slices and discard the sousing liquid.
To serve, spoon the cauliflower purée into the centre of the serving plates and place three paupiettes of plaice on top. Pile a spoonful of crabmeat on top then finish with a few pieces of turnip. Scatter the coriander cress around and drizzle over some coriander oil.