2 carrots, sliced
2 leeks, sliced
1 onion, chopped
2 shallots, finely chopped
2 sprigs fresh tarragon, plus 1 tsp freshly chopped
2 tbsp plain flour
1 bay leaf
salt and freshly ground black pepper
6 peppercorns
70ml/2陆fl oz white wine vinegar
40驳/1陆辞锄 butter, plus extra for greasing
300g/10陆oz unsalted butter
4 free-range egg yolks
600g/1lb 5oz cod loin, skinned and cut into 3cm/1in chunks
50ml/2fl oz dry white wine