Rhubarb-Lemon Bars with Pistachio Crust

Lemons intensify rhubarb’s floral tartness while asserting their own citrus tang in this pink take on the American classic. I often cook the fruits together, and once, after making a rhubarb-lemon syrup for a cocktail, I was left with a strainer full of what looked like stringy rhubarb pulp. But it didn’t taste stringy at all—it was as smooth as lemon curd. I spread some on shortbread and immediately knew rhubarb was the answer to creating a more delicious lemon bar. It makes the lemon layer fruitier, creamier, and altogether more luscious. The whole wheat pistachio crust stays crisp underneath and enriches the lightness of the top.

TIP: To make the filling a pretty pink color, use only very red rhubarb. Fruit with hints of green or yellow will turn the topping taupe.

makes 1 dozen

Pistachio Crust

Rhubarb-Lemon Layer

1. To make the crust: Position a rack in the center of the oven and preheat to 350°F. Coat an 8-inch square baking pan with nonstick cooking spray. Line the bottom and sides with foil or parchment paper and spray again.

2. Combine the pistachios, flour, sugar, and salt in a food processor and process until the nuts are finely ground. Zest the lemon into the mixture (save the lemon for the top layer). Add the butter and oil and pulse until the dry ingredients are evenly moistened and small clumps form; scrape the bowl occasionally. Press the clumps into an even layer in the prepared pan. To get a completely flat bottom, press in the mixture with the bottom of a dry measuring cup. (Return the bowl to the processor; there’s no need to wash it.)

3. Bake until the crust is golden brown, 16 to 18 minutes. Transfer to a wire rack. (Leave the oven on.)

4. Meanwhile, make the rhubarb-lemon layer: Combine the rhubarb, ½ cup (104 g) sugar, and 2 tablespoons lemon juice in a small saucepan and bring to a boil over medium heat, stirring occasionally to dissolve the sugar. Continue boiling until the rhubarb breaks down, about 3 minutes. Transfer to the food processor and let cool slightly.

5. Process the rhubarb mixture until smooth. Add the salt and the remaining ⅓ cup (69 g) sugar and ½ cup (112 g) lemon juice and process until smooth, scraping the bowl occasionally. Sprinkle the flour over the mixture and pulse until incorporated. With the machine running, add the eggs one at a time, processing just until smooth. Pour the rhubarb mixture over the crust (it’s fine if the crust is still hot or warm).

6. Bake until the top is just set, 20 to 22 minutes.

7. Cool completely in the pan on a wire rack. Cover the pan with plastic wrap and refrigerate until the bars are cold and the filling no longer jiggles, at least 2 hours.

8. Lift the bars out of the pan using the sides of the foil or paper. Cut into thirds, then cut into quarters to form 12 bars.

MAKE AHEAD

The bars are best the day they’re made but will keep in the refrigerator for up to 2 days.