For the sorbet, mix together the tea leaves, caster sugar and lemon juice in a heatproof bowl. Pour over the boiling water and set aside to steep for at least 30 minutes.
When the mixture has steeped, strain it through a fine sieve into an ice cream maker. Churn the mixture, according to the manufacturer's instructions, until almost frozen, then transfer to a freezable container and place in the freezer until set.
(NB: To make the sorbet without an ice cream maker, freeze the mixture in a freezable container for one hour, then remove and stir to break up the ice crystals. Repeat the freezing and stirring process 2-3 times, until the sorbet is frozen solid.)
Meanwhile, for the strudel, preheat the oven to 190C/375F/Gas 5.
Stand the pears in the bottom of a saucepan. Add the tea leaves, caster sugar and lemon juice, then pour over enough cold water to just cover the pears. Bring the mixture to the boil, stirring carefully.
When the liquid is boiling, reduce the heat until it is simmering. Poach the pears for 15-20 minutes, or until tender. Drain the pears, rinsing off any tea leaves that stick to them, then set aside to cool slightly.
When the pears have cooled, cut them into quarters, remove the cores, then chop roughly.
In a bowl, mix together the chopped poached pears, sultanas and almonds until well combined.
Mix together the soft brown sugar and ground cinnamon, then fold the mixture into the pear mixture until well combined.
Lay the filo pastry onto a work surface lightly dusted with icing sugar. Overlap the sheets of pastry slightly to form a rectangle about 40cm x 30cm/16in x 12in. As you layer the filo pastry sheets, brush each sheet all over with the melted butter.
Continue to add the remaining filo pastry sheets in layers, brushing each sheet with more of the melted butter, until all the filo pastry and butter is used.
Sprinkle the pear mixture onto the filo pastry rectangle, leaving a 2.5cm/1in free at the edges of the rectangle.
Fold the free edges of the long sides of the rectangle back over the pear mixture. Starting at one end of the shorter sides of the rectangle, roll up the filo pastry and pear filling to form a swiss roll.
Transfer the filo pastry roll to a baking tray and dust all over with the icing sugar. Bake in the oven for 40-45 minutes, or until the pastry is crisp and golden-brown.
To serve, slice the cinnamon strudel and place one slice into the centre of each serving plate. Sprinkle some of the rich tea biscuits in a pile alongside the strudel. Place a scoop of the Earl Grey sorbet on top of the crumbled rich tea biscuits.