Sea bass in puff pastry

Name: Sea bass in puff pastry
Ingredients: 60g small cooked prawns, peeled and finely chopped; 2 tbsp finely chopped tarragon; 1 tbsp olive oil, plus extra for greasing; 1 large free-range egg, beaten; 2 tbsp milk; Plain flour, for dusting; 500g pack of puff pastry, halved; 1kg whole sea bass, filleted (ask your fishmonger to do this); Green salad, to serve; SALSA VERDE; 1 small bunch each of basil, mint and flat-leaf parsley, leaves picked; 2 garlic cloves; 6 cornichons; 2 tbsp capers, drained; 3 anchovy fillets, drained; 5 tbsp olive oil; 1 tbsp red wine vinegar