3 Large beetroots
200 g (7.1oz) Rock salt
70 g (2.5oz) Unsalted butter, softened
70 Caster sugar
10 g (0.4oz) Flour, for dusting
100 g (3.5oz) Puff pastry (ready made is fine)
1 Egg, lightly beaten
Preheat the oven to 1 80 degrees C/350 degrees F/gas mark 4. Wrap each beetroot individually in foil and place them on a roasting tin lined with rock salt. This helps to draw out moisture, even when the beets are wrapped in foil. Bake in the oven for 1 1/2 hours. Remove the beetroot from the oven and set aside to cool in the foil - they will steam a little, which makes them easier to peel. Save the salt to use again. When they are cool, peel the beetroot, cut them into quarters and set aside. Evenly cover the base of the frying pan with the butter - use your fingers, really squashing the butter down. Then sprinkle the sugar evenly over the butter. Place the pan over a medium heat until the butter melts and the sugar starts turning a light golden colour. Now place the beetroot quarters on top, arranging them in concentric circles until they are all used up. Set aside to cool. On a floured surface, roll out the puff pastry to a thickness of 3mm. Pay attention to the size as you are rolling: the pastry must be big enough to cover the beetroot in the pan. Place the puff pastry gently over the top of the beetroot, tucking any excess pastry between the beetroot and the pan like a blanket. Brush the pastry with the beaten egg. Put the tart in the oven for about 40 minutes, or until golden brown and oozing caramel slightly at the edges. Remove from the oven and turn out onto a plate to serve.