1. Bring a pan of salted water to the boil. Make a bag out of wide foil by tearing off a piece 35 x 45cm in size and folding it double. Fold three sides up, sealing it by brushing a little beaten egg onto the edges before you fold. Leave one side open.

2. Cut the potatoes into quarters (large potatoes into eighths). Drop them into the boiling salted water and cook for 6 minutes. Meanwhile, place the fennel, lemon slices, cherry tomatoes, oil, olives and fish in a large bowl. Season and gently combine.

3. Drain the potatoes, cool and add to the bowl. Mix everything together, scoop into the foil bag and sprinkle on the fennel fronds. Seal the remaining edge loosely and write the cooking instructions on it with a marker. Pop the bag in the fridge – it’ll keep there for a day or two.

4. Heat the oven to 200ºC/400ºF/gas 6, unravel one side of the bag and pour in the wine. Reseal the bag, place on a baking tray and cook for 18 to 20 minutes (if the piece of fish is quite thick, it’ll need 25 minutes).

5. Once cooked, place the bag on a serving plate and gently pierce to release the steam. The tomatoes and wine will have made a delicious sauce. Lovely with some steamed broccoli or green beans.