<p>Seriously delicious recipe ALERT. Imagine baking the best dessert this spring? Here you have it. It has all this awesome elements and it's an incredible combination of sour yet sweet. Crunchy and flaky, yet creamy and airy. We decided to use puff pastry, because it gives you this awesome flaky texture and on the other hand the sabayon is soft, delicate and creamy. The rhubarb is a nice combination of sour and sweet which really makes our senses happy. We absolutely adore this recipe. It's easy to make, great for picnics or even birthday parties plus you can leave your own personal touch with a creative pattern on top of each mini hand pie. Heavenly good! </p>
Add the elderflower cordial, limoncello and lemon zest to a saucepan. Place it over medium-high heat. Halve the vanilla bean and scrape out the seeds. Add them to the saucepan and bring to a boil. Remove the saucepan from the heat and set aside until needed.
Poach the rhubarb
Cut the rhubarb stalks onto 4cm /1.5 inch long stalks. Add these stalks to a large bowl and pour the warm poaching liquid over it. Leave it for about 20 minutes to marinate.
Mini rhubarb pies
Preheat the oven to 200 °C / 390 °F. Dust the working area with a bit of flour and roll out your puff pastry into a rectangle about 2mm thick. Cut the dough into 8 equal rectangles, each should be about 8 cm x 12 cm (3 inch x 4.5 inch). Drain the rhubarb stalks and save the poaching liquid.
Mini rhubarb pies
Place 4 - 5 marinated rhubarb stalks in the center of the rectangle. Repeat the process until you get four rectangles filled with rhubarb stalks. Gently dust the rhubarb stalks with a bit of icing sugar and lemon zest. Cover the rhubarb stalks with the remaining pastry. Pinch the dough together at the edges to seal. Place the rhubarb mini pies on the baking sheet, covered with parchment paper.
Beat the egg yolk in a small bowl. Using a kitchen brush, gently brush the mini pies. On top of each pie, using a knife cut out a random pattern to make it look even prettier. Sprinkle with pearl sugar. Place the baking sheet in the oven and bake for 20 minutes at 190 °C / 375 °F.
Add the egg yolk, poaching liquid, limoncello and caster sugar to a glass bowl. Place the bowl over a saucepan of simmering water, ensuring that the bottom of bowl does not touch the water. Using a hand-held electric mixer, whisk the mixture for about 6 minutes, or until thick, pale and doubled in volume. Remove the bowl from the heat and place it in a larger bowl, filled with ice cold water, to cool the sabayon, but do not stop mixing. Cover with a plastic wrap and place in the fridge until needed.
Place the baked pies on the wire rack for about 10 minutes to cool. Serve the rhubarb mini hand pies with a dollop of sabayon cream and leftover marinated rhubarb.