Heat the oil in a dish large enough for all the beetroot to sit snugly, add the beetroot and toss to coat in the oil .
Add the syrup, vinegar and seasoning.
Cover the pan with foil and place in an oven preheated to 190°C for approximately 30-40 minutes or until the beetroot are tender.
When the beetroot are cooked remove from the oven and arrange the beets neatly in the dish, flat side upwards.
Roll out the pastry and cut a circle a little larger than the pan. Carefully place the pastry over the beetroot tucking the excess pastry into the pan. Return to the oven and cook for 20-25 minutes until golden and puffed up.
Make the vinaigrette by placing all the ingredients in a bowl and give it a good stir.
When the tart is ready remove from the oven and leave to rest for a few minutes.
To serve place a large plate over the dish and carefully, but quickly, turn upside down remove the pan and pour over the vinaigrette.