To make the hazelnut butter, mix all the ingredients and season with pepper.
Put two cleaned scallops back into each shell and divide the hazelnut butter between them. Season with a pinch of sea salt.
Replace the lids of the scallop shells and cook on a barbecue or under a hot grill for 3-5 minutes.
To make the French dressing, whisk together the mustard and vinegar. Season with salt and pepper, slowly whisking in the oils. Use to dress the salad leaves and herbs.
Serve the cooked scallops, on piles of wet sea salt with the dressed salad.