1 unwaxed lemon, finely grated zest
1 tbsp lemon juice
1 tbsp chopped fresh tarragon
salt and freshly ground black pepper
60g/2¼oz panko breadcrumbs
dash caster sugar
40g/1½oz butter
200g/7oz crème fraîche
40g/1½oz Parmesan, coarsely grated
4 sea bass fillets, skin on