Step 1

Heat oven to 200C/180C fan/gas Put the potatoes in a large roasting tin and drizzle with the oil. Season and roast for 20-25 mins.

Step 2

Take the roasting tin out of the oven, turn the potatoes over and add the tomatoes and asparagus, nestling among the potatoes.

Step 3

Place the fish on top and squeeze over the lemon. Top each fillet with a smear of butter, season and return to the oven for a further 10-12 mins or until the fish is cooked and the vegetables are tender.