Roast cod with lemon beurre blanc and winter ratatouille

Ингредиенты

• 175g/6oz swede
• 175g/6oz parsnip
• 175g/6oz carrot
• 175g/6oz beetroot
• 175g/6oz butternut squash
• 1 onion
• 2 garlic
• 5-6 tbsp olive oil
• salt and freshly ground black pepper
• 2 shallots
• 1 tbsp white wine vinegar
• 1 lemon, zest grated, plus 4-5 tbsp lemon juice
• 4 tbsp white wine
• 1 tbsp cold water
• 225g/8oz salted butter
• salt and freshly ground black pepper
• 1 tbsp vegetable oil
• 1 tbsp butter
• 6 x 110g/4oz cod fillets, preferably line-caught, skin on, (fillets cut from the middle of the fish
• salt and freshly ground black pepper