Rhubarb is such a sight for winter-sore eyes. This harbinger of spring usually takes a back seat to strawberries when used in pastry, but it absolutely shines when used on its own or paired with other flavors. I love to pair it with orange zest and round things out with vanilla, nestle it onto a small round of puff pastry, then finish it with a sprinkling of turbinado sugar. Once exposed to heat, the rhubarb collapses and goes a bit jammy while the sugar caramelizes, glazing the whole pastry with a sweet, crackly veneer that plays well with the flaky pastry.
If you’ve never worked with rhubarb, remember not to eat the leaves. They contain anthraquinone glycosides and oxalic acid, an unfriendly combination that you want to avoid. The stalks, however, are safe to eat, and are usually sold sans-leaves.
3/4 cup brown sugar
Seeds scraped from 1 vanilla bean
Zest from 1 medium orange
1 lb rhubarb, ends trimmed, sliced on a bias about 1/3″ thick
1 1/2 tablespoons corn starch
2 sheets puff pastry
1 egg, beaten, for egg wash
Demerara or Turbinado sugar, for sprinkling
1. In a medium bowl, stir together the brown sugar, vanilla bean scrapings, and orange zest. Use your fingers to rub the vanilla and zest into the sugar a bit. Add the rhubarb and toss well with the sugar. Add the corn starch and toss again.
2. Let the rhubarb mixture sit at room temperature for about an hour. Give it a good stir several times during the hour, scooping sugar and juices from the bottom of the bowl and mixing everything together well each time.
3. After about an hour, once the sugar and rhubarb juices have formed a syrup, preheat the oven to 375 degrees and line 2 baking sheets* with parchment paper.
4. Remove the puff pastry from the refrigerator and, on a lightly floured surface, roll it out until it is between 1/8 and 1/4″ thick, keeping it closer to 1/8″. Use a round cutter to cut rounds from the pastry (or just use a very sharp knife to cut squares, if you wish), then place each round onto the parchment lined baking sheet, leaving enough room for expansion. If at any point the pastry becomes warm, stop what you are doing and place it in the fridge for about 20 minutes, then continue.
5. Use a pastry brush to lightly brush the egg wash over the puff pastry rounds, then spoon about two tablespoons of the rhubarb mixture onto the rounds, making sure to include a little bit of the syrup. Sprinkle each pastry with demerara sugar, then bake for about 20-25 minutes or until the pastry is golden brown and puffy. Baking time will depend on how thin you rolled the pastry, so start checking around 15 minutes.
6. Once the tarts are baked, remove the baking sheets from the oven and place on a cooling rack. Let cool for at least ten minutes before serving, though these are best at room temperature. Serve the same day as you bake them.
*I suggest baking these one tray at a time. Prep tray #2 while tray #1 bakes, then place it in the refrigerator until it is time to bake it.