Heat oven to 375F/180C.

In a bowl, toss the beetroot and onion in 2 tablespoons of the oil, the vinegar, sugar and molasses or honey. Add the star anise and season well with salt and pepper.

Heat the remaining olive oil in a large, ovenproof non-stick frying pan, then add the beet and onion mixture, covering the surface of the pan. Cover with foil and bake for 45 minutes.

On a well-floured surface, roll the pastry a little, making it large enough to cut out a circle the same size as your frying pan. Carefully take the pan out of the oven, remove the foil and wiggle the beets and onion around in the pan to make a compact layer. Put the pastry on top, tucking it in all around the edges, then return the pan to the oven and bake for another 35 minutes, or until the pastry has puffed up and is a deep golden brown.

To serve: Slide a knife around the edge of the tart, then put a plate on top of the pastry, serving side down. Flip the pan over to turn the tart out onto the plate – wear oven mitts when you do this and be careful not to burn yourself with the handle. Top with the orange zest and a sprinkle of sea salt.