Heston Blumenthal's pan-seared cod with leek and potato sauce recipe

Ingredients

• 50 g potato, peeled and finely sliced
• 10 g unsalted butter
• 1/2 onion, peeled and finely sliced
• 160 g leeks, washed and v. finely sliced
• 200 ml fish stock, warmed
• 1 bouquet garni
• 1 tbsp whipping cream
• 1 tbsp whole milk
• 1 tbsp groundnut oil
• 300 g cod fillets
• 1 bunch chives, finely chopped
• 20 g pea shoots, to garnish