‘Fish pie’ soup

Melt the butter from the Parmentier potatoes in a heavybased casserole and add the potatoes and leek, stirring to coat in the butter; season and cook for 5 minutes. Bring a kettle of water to the boil. Mix the fish sauce into 250ml just-boiled water and add to the pan with the cider. Bring to the boil, then lower to a simmer and cover with a lid; bubble away for 10-12 minutes until the potatoes are tender.

Tip in the fish pie mix and petit pois, bring back to a simmer and cover with a lid; cook gently for 3-5 minutes or until the fish is cooked through and opaque. Stir through 1 tbsp crème fraîche.

Meanwhile, mix the remaining 2 tbsp crème fraîche, tarragon, lemon zest and juice. Divide the soup between 2 bowls and serve with a dollop of herby crème fraîche, freshly ground black pepper and the lemon wedges on the side for squeezing over.