One-pan roast fish

Method

1. Preheat the oven to 180°C/fan160°C/gas 4. Peel and slice the potatoes and layer in a roasting tin. Drizzle with olive oil, dot with butter and season. Roast for 25 minutes.
2. Meanwhile, heat 1 tbsp olive oil in a pan over a low heat and fry the onions for 5 minutes. Add garlic and cook for a further 2 minutes. Pile onto the potatoes, then top with tomatoes, parsley, tarragon sprigs and fish fillets. Drizzle with olive oil and the juice of 1 lemon. Season well, top with lemon slices and bake for 10-12 minutes until the fish is cooked through.