Fish Chowder

Ingredients

• 20g butter
• 1 tbsp olive oil
• 1 brown onion, finely chopped
• 2 sticks celery, finely diced
• 1 large carrot, finely diced
• 2 large potatoes, peeled, diced
• 1/4 cup plain flour
• 1 cup fish stock
• 4 cups water
• 1 lemon, finely grated rind and 2 tbsp juice
• 3 50g thick white boneless fish fillets, cut into 3cm pieces or salmon fillets
• 500g cleaned cockles
• ½ cup small flat-leaf parsley leaves
• small dinner rolls, to serve
• butter, to serve