Open the roasting vegetables and pour into a bowl, keeping the herb butter to one side for the caramel. Wipe the base of the dish clean with some kitchen paper.
In a clean, small saucepan, put the caster sugar and vinegar, mix with your finger. Place the sugar and vinegar over a high heat for 2–3 minutes until you have a dark rich caramel. It will be thick, and you will be able to smell when it is ready—the strong vinegar smell will be gone, and you will smell the sweet caramel. (160°C if you have a thermometer.) Add the butter and mix well.
Pour the caramel into the cleaned vegetable foil dish. Put the marinated vegetables back on top.
Cut the puff pastry so it overlaps the foil dish by about 3 cm. Cover the vegetables with the puff pastry and tuck the extra puff down the sides of the vegetables. Using a fork, prick the puff pastry all over. Place the finished foil dish on a baking tray.
Bake in a preheated oven at 180°C for 55 minutes. Leave to rest for 5 minutes and then turn out the tart.
Garnish with the feta, tomatoes, picked herbs, olive oil, and black pepper. Serve with a dressed side salad.
