The classic tarte tatin is made, of course, with apples. But the principle of caramelising some delicious, round, sweet things, topping them with puff pastry, then flipping it upside down, works equally well in this savoury interpretation. The shallot/spring onion vinaigrette finishes off the tarte a treat – but, if you fancy ringing the changes, it’s also very good topped with crumbled feta and coarsely chopped parsley.
Preheat the oven to 190°C/Gas Mark 5. Roll out the pastry on a lightly floured surface to a thickness of about 5mm. Take an ovenproof frying pan (or a tarte tatin dish) roughly 20cm in diameter, place it upside down on the pastry and cut around it. Wrap the pastry disc and place it in the fridge.
Melt the butter with the oil in the frying pan (or tatin dish). Add the cider vinegar, sugar and some salt and pepper, stir well, then add the halved beetroot and toss in the juices. You want the beetroot to fill the pan snugly, so add a few more if you need to. Cover the pan with foil, transfer to the oven and roast for 30–40 minutes, until the beetroot are tender.
Take the pan from the oven and rearrange the beetroot halves neatly, placing them cut side up. Lay the pastry disc over the beetroot, patting it down and tucking in the edges down the side of the pan. Return to the oven and bake for 20 minutes, until the pastry is fully puffed up and golden brown.
Leave the tarte to cool in its dish for about 15 minutes, then turn it out by putting a plate over the top and inverting it. Pour any juices left in the pan back over the beetroot.
Put the ingredients for the vinaigrette into a screw-topped jar, season well with salt and pepper and shake to combine. Trickle over the tarte tatin and serve.