1) Mix the flour, sugar, and lemon peel, in a food processor. Add the butter. Pulse until the mixture resembles a coarse meal. Add salt. Pulse in the ice water, 1 tbsp at a time, until moist clumps form. Gather the dough into a ball; flatten into a disk. Wrap the dough in cling film and refrigerate until firm, about 1 hr.
2) Position the rack in the centre of the oven and preheat the oven to 200°C/ gas mark 6. Roll out the dough on a floured surface to an 28cm round. Transfer the dough onto a heavy baking sheet that has been lined with a silpat or parchment paper. Stir the lemon juice into the preserve and spread the preserves on top of dough, leaving a 5cm border. Fold the dough border over the filling to form an 20cm round, pleating loosely and pinching to seal any cracks in the dough.
3) Bake the crostata until the crust is golden, 35 to 40 mins. Allow to cool. Sprinkle with the almonds and dust with the icing sugar, if you wish. Slide a metal spatula under the crust to free the crostata from the baking sheet and serve.