Lay two large pieces of foil on the kitchen benchtop, shiny side facing down, and place a slightly smaller piece of baking paper onto each piece of foil.
Arrange the vegetables in the centre of the paper with the preserved lemon.
Add the thyme, fish, olive oil, lemon juice and season with black pepper.
Wrap the paper and foil around the fish and secure it into 2 loose parcels.
Place the parcels onto a baking tray and cook in the oven for 30 minutes.
Transfer onto a plate to serve or leave it on the baking paper.