1. Preheat oven to 200°C. Cut four 40cm squares of baking parchment or tin foil. Grate zest from the lemon, then put into a small bowl with butter and plenty of seasoning. Stir to combine, then set aside. Slice the zested lemon into thin rounds.
2. On one half of each square, pile a quarter each of the beans, fennel and baby marrow. Top each pile with a fish fillet, then lay over some lemon slices. Dab a quarter of the butter onto each pile of vegetables and fish, then add the dill sprigs and some seasoning. Spoon 2 tbsp water onto each pile. Seal the parcels by pulling the empty side of the baking parchment or foil up over the filling, then folding the edges.
3. Put the parcels on baking sheets and cook in the oven for 18 to 20 minutes. To test whether the fish is cooked without opening the parcel, press the fish through the baking parchment or foil – it should feel as though it’s flaking. Transfer the parcels to plates and bring to the table with some salad and bread to mop up the juices.

EACH SERVING About 1 075kJ, 10g fat (5g saturated), 14g carbohydrate (2g total sugars).