- 1 pound rhubarb, cut into 2-inch pieces
- 1 cup sugar
- 1 cup elderflower syrup (see Note)
- 2 to 3 tablespoons fresh lemon juice
- 1 1/2 sticks unsalted butter, cubed, plus more for greasing
- 2 1/4 cups old-fashioned rolled oats
- 3/4 cup barley flour
- 3/4 cup barley flakes
- 1 cup packed dark brown sugar
- 1 teaspoon baking powder
- 1/4 teaspoon kosher salt
- 1/2 teaspoon thyme leaves
- 1 tablespoon water
- 1 1/4 cups skyr (Icelandic yogurt) or Greek yogurt
- 1/4 cup sugar
- 1/2 teaspoon finely grated lemon zest
- 1 teaspoon rose water (optional)
- 1 cup heavy cream
How to make this recipe
Make the rhubarb jam
In a medium saucepan, combine the rhubarb, sugar and elderflower syrup and bring to a simmer. Cook over moderately low heat, stirring occasionally, until thick, 50 minutes to 1 hour. Scrape the jam into a heatproof bowl and let cool to room temperature. Stir in the lemon juice.
Make the tart
Preheat the oven to 350°. Butter a 10-inch fluted tart pan with a removable bottom. In a bowl, whisk the oats with the barley flour, barley flakes, brown sugar, baking powder, salt and thyme. Using your fingers, blend the cubed butter into the oat mixture; blend in the water until well incorporated. Firmly press two-thirds of the mixture evenly over the bottom and up the side of the tart pan.
Spread 1 1/2 cups of the rhubarb jam in the tart shell; reserve the remaining jam for another use. Pinch the remaining dough into large crumbs and scatter over the jam. Bake the tart for about 40 minutes, until the topping is deep golden. Transfer to a rack to cool completely.
Meanwhile, make the topping
In a bowl, whisk the skyr with the sugar, lemon zest and rose water, if using. In another bowl, beat the cream to stiff peaks. Fold the whipped cream into the skyr. Serve the tart with the whipped skyr.
The jam can be refrigerated overnight; bring to room temperature before using. The baked tart can be kept covered at room temperature overnight.
Elderflower syrup is available at many specialty food stores and from kalustyans.com. Alternatively, substitute St-Germain elderflower liqueur.