One-pan roast herby fish

Method

1. Scatter the potatoes and onion into a large roasting tray. Drizzle with 1 tbsp oil, season, then toss to coat. Dot with butter, then cook in the oven for 15 minutes at 190C/fan170C/gas5. Add the tomatoes, then return to the oven for 10 minutes more. Meanwhile, whizz the anchovy, garlic, lemon zest and parsley in a food processor with 3 tbsp of the olive oil to make a gremolata. Taste and season.
2. Mix the breadcrumbs with 2 tbsp oil and some seasoning. Top the potatoes with the fish fillets, lemon slices and sliced chilli, then scatter with the breadcrumbs.
3. Return to the oven and cook for 12-15 minutes until the fish steaks are just cooked through and the breadcrumbs are golden. Remove from the oven, top with the herby gremolata, then serve.