For the shortbread, combine the butter, sugar, lemon and vanilla pods and mix until smooth and pale. Add the flour and mix until just combined. Press, wrap in cling film and set aside in the fridge for 15 minutes
Preheat the oven to 190°C/gas mark 5. Roll out your dough to a thickness of 0.5cm and place in a shallow baking tray. While the dough is still raw, cut into small equal rectangles and sprinkle evenly with caster sugar. Bake in the oven for 15-20 minutes making sure the biscuits cook without browning
Start on the sabayon by whisking together the yolks, sugar and champagne in a large heatproof bowl. Place the bowl over a pan of simmering water, making sure the water does not touch the base of the bowl
Continue to whisk until the mixture thickens. Remove from the heat and continue to whisk occasionally while it cools. Gently fold the cream through the cool champagne mixture
To serve, place some strawberries at the bottom of tall glasses, together with some of the poaching liquid. Spoon over some of the champagne sabayon and serve with the shortbread biscuits.