Lighter fish chowder

INGREDIENTS

• 1½ tbsp rapeseed oil
• 3 slices prosciutto , trimmed of fat, cut into strips
• 2-3 leeks , thinly sliced (about 320g trimmed weight)
• 2 plump garlic cloves , finely chopped
• 3 thyme sprigs (preferably lemon thyme), plus extra leaves to garnish
• 2 bay leaves
• 650g floury potatoes such as Desiree or Maris Piper, unpeeled, scrubbed, sliced 5mm thick
• 600ml hot vegetable stock from a good-quality cube or powder (we used Marigold bouillon)
• good pinch of chilli flakes
• 250g skinless salmon fillets
• 250g skinless pollack or haddock fillets
• 3 tbsp half-fat crème fraîche
• snipped chives , to garnish