Preheat the oven to 200°C/ 180°C fan/ Gas 6.
Unroll the puff pastry onto a baking tray (it should already have the greaseproof paper attached). Score a 1.5cm border around the outside edge.
Make the filling by adding all the ingredients (apart from the pastry and rocket) to a bowl and mix well. All the vegetables should be coated in the oil, herbs and seasoning.
Transfer the vegetable mix onto the puff pastry sheet, spread evenly leaving the border clear.
Place into the oven on the middle shelf and bake for 25-30 minutes. All the vegetables should be cooked, and the border of the pastry risen and golden brown in colour.
Remove from the oven and dress with the rocket leaves.
Slice into 6 squares and serve just as it is. Great for parties and picnics too!