Cut rhubarb into 3 – 4 cm chunks and place in a shallow dish, scatter over 100 g caster sugar and the zest and juice from a small orange.
Cover and bake in a 170°C oven for 20-30 minutes, until just soft. Let this cool.
Make some pastry as follows. Put 150g plain flour into a food processor along with a pinch of salt, a tsp caster sugar and a tsp ground ginger
and whizz for a couple of seconds, then add 100g cold butter cut into small chunks and process briefly until it starts to come together.
Tip out and knead briefly until smooth, then wrap in clingfilm and chill for 30 minutes. Roll out the pastry and line a 23 cm tart tin,
chill for another 30 minutes, then line with baking parchment (easy if you cut a disk of paper larger than the tin, and scrunch it up tightly,
then unfurl and line the pastry tart), fill with baking beans and bake in a 180°C oven for 20 minutes. Remove the beans and parchment and bake
for another 5 minutes, to finish cooking the base. Let cool and transfer to a serving plate.
Make some custard by beating 2 egg yolks with 50 g caster sugar until pale and frothy. Heat 100 ml double cream and 100 ml whole milk until
nearly boiling and pour this into the beaten eggs, whisking as you pour, then tip the whole lot back into the saucepan and heat gently,
stirring all the while, until the custard thickens. Remove from the heat and let cool. Process half the rhubarb to a smooth puree and stir
this into the custard, then pour the mixture into the pastry shell. Top the custard with the remaining rhubarb.
Now make some meringue for the final touch. Measure out about 150 ml of the rhubarb liquid and bring to a boil. Whisk 2 egg whites until stiff,
then add a ½ tsp cream of tartar. Carefully pour the boiling sugar syrup into the egg whites, whisking all the time, until you have a smooth
glossy meringue. Fill a piping bag fitted with a star nozzle and pipe little peaks of meringue over the tart.
Use a blowtorch to gently brown the meringue and serve straight away.