First, preheat your oven to 170C (150C fan) – don’t go any higher than this. Peel your pears, then cut them into quarters lengthways, cut out the very core, then cut each quarter in half again.
To an ovenproof frying pan, add your butter, sugar, lemon juice and salt and heat to dissolve the sugar. Slice the vanilla pod in two and scrape in the seeds. Add the pod, too. Be careful from now on; caramel burns can be horrific.
Remove from the heat once boiling and arrange your pear slices on the hot caramel. Return to the heat and boil furiously (without stirring, just swivel the pan) for at least 10 minutes – you want the caramel to turn a golden brown colour.
Whilst boiling, roll out your pastry until it is half a centimetre thick (or less). When the fruity caramel has browned and reduced, carefully lay your rolled-out pastry on top. Cut around the edge and tuck any excess down the side of the fruit.
Bake in the oven for about 40 minutes – it should be a deep golden brown on top, even though it’s been baked at quite a low temperature.
Once done, leave to cool for 5 minutes, then place a large plate on the hot pan. Carefully, but quickly and decisively, flip the pan and plate over so the pastry is underneath and the fruit is on top. Garnish with the vanilla pod, and serve hot or cold.
If you don’t have an ovenproof frying pan, just caramelise the pears in a normal frying pan and when ready, pour them into a cake or tart tin – pick one that’s not going to leak everywhere. Then, simply put the pastry on top as normal.