Heat the oven to 220C/200C fan/gas 7. Cut 600g of the strawberries into bite-sized pieces (no need to remove the stalks) and scatter over a roasting tray with the vanilla pod and seeds, the lemon juice and 50g sugar. Roast for 20-25 mins, or until very soft. Remove from the oven and discard the vanilla pod, then transfer the berries to a food processor and blitz until smooth. Pass through a fine sieve, then tip the purée into a wide pan. Slice 200g of the remaining strawberries (this will be all of the remaining strawberries if making individual tiramisus) and stir these into the purée. Bring to a simmer over a high heat and cook for 4-5 mins until reduced and thickened. Remove from the heat and cool fully. Will keep chilled for three days.

Separate the egg yolks and whites between two bowls, then tip the remaining sugar into the egg yolks. Beat using an electric whisk until thick, pale and fluffy, about 5 mins. Beat in the mascarpone, a little at a time, until smooth. Set aside.

Clean the beaters well, then whisk the egg white to stiff peaks, about 5 mins. Add a large spoonful of the whipped egg whites to the egg yolk mixture and stir to combine, then gently fold in the remaining egg whites using a large metal spoon.

Put the teabag in a shallow heatproof dish and pour over 150ml hot water (about 60C). (Boiling water will affect the delicate flavour of the tea.) Steep for 1-2 mins, then remove the bag and discard. Stir in the elderflower liqueur or cordial. Turn the sponge fingers in this for a few seconds on each side until soaked but not too wet or soft. Arrange in a 30 x 20cm baking dish in one layer. Spoon over half the strawberry purée mixture, then half the mascarpone mixture. Repeat with a second layer of the sponge fingers and the remaining mixtures. (Or, layer the fingers and mixtures in dessert glasses – you may need to roughly break up the fingers to fit.) Chill for at least 6 hrs, or overnight. Will keep chilled for up to two days.

Dust with the crushed freeze-dried strawberries, if using. Slice any remaining fresh strawberries, dot over the top and serve.