Sourdough Lemon Bars

This post may contain affiliate links. Please read our disclosure policy.

These sourdough lemon bars have a buttery shortbread crust and a bright, silky lemon curd that sets into clean, bakery-style squares.

The crust is enriched with sourdough discard, vanilla, and fresh lemon zest, giving it a tender crumb and subtle depth of flavor that pairs beautifully with the vibrant citrus filling.

The lemon layer is cooked gently on the stovetop before baking to ensure a smooth, glossy curd that slices neatly once chilled. The result is a delicious sourdough dessert with bold lemon flavor and a buttery shortbread base.

Lemon desserts are a favorite of mine, especially in the spring and summer months. These sourdough discard lemon bars will be a favorite for lemon lovers!

I think these bars would be so perfect for an Easter dessert, a Mother’s Day brunch, or tea party.

For more sourdough discard recipes, try our sourdough lemon bread, sourdough lemon poppy seed scones, and sourdough blueberry bread.

Why You’ll Love Sourdough Lemon Bars

Make-Ahead Friendly: These sourdough discard lemon bars are best served chilled, and they’re an excellent make-ahead dessert for gatherings since the texture improves after several hours in the refrigerator.
Great Use of Extra Sourdough Starter: If you have extra sourdough starter discard that needs to be used, this is a great recipe to make.
Simple Ingredients: This recipe uses simple ingredients and pantry staples, in addition to fresh lemons.

Ingredients

Find the full list of ingredients, amounts, and instructions in the printable recipe card at the bottom of this post.

Fresh Lemons: Using fresh lemon juice instead of bottled lemon juice is key to the best lemon flavor. This lemon bar recipe was tested with Meyer lemons, but regular lemons will work just as well.
White Sugar: Provides sweetness
All-Purpose Flour: To create the buttery sourdough shortbread crust that is the foundation for these classic lemon bars.
Sourdough Starter: Use sourdough discard or active starter.
Eggs: Used to make the lemon custard filling.

How to Make Sourdough Lemon Bars

Here are the step-by-step instructions for making sourdough lemon bars.

Step 1: Preheat the oven to 350°F. Line an 8×8-inch metal baking pan with parchment paper, leaving an overhang on the sides to help lift the bars out later.

Collage of four photos showing steps 1-4 for how to make sourdough lemon bars.

Step 2: In the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter for about 20–30 seconds until smooth (Photo 1). Add the granulated sugar and mix for 1–2 minutes until fully combined and slightly lighter in color, but not fluffy. Mix in the vanilla extract, lemon zest, and kosher salt. Add the sourdough discard and mix until fully incorporated (Photo 2).

Step 3: In a separate bowl whisk together the flour and cornstarch. Add the dry ingredients to the mixer and mix on low speed just until the dough comes together and no dry streaks remain. Do not overmix.

Step 4: Press the dough evenly into the prepared pan (Photo 3). If the dough feels sticky, you can use the saved butter wrapper or the bottom of a measuring cup to help smooth it into an even layer.

Step 5: Bake for 18–22 minutes, or until the edges are lightly golden and the center is set. Allow the crust to cool slightly while preparing the lemon filling and reduce the oven temperature to 325°F (Photo 5).

Collage of four photos showing steps 5-8 for how to make sourdough lemon bars.

Step 6: Place the cold cubed butter in a bowl and set a fine mesh strainer over the top. In a medium saucepan combine the sugar and lemon zest. Rub the zest into the sugar with your fingers for about 30 seconds to release the lemon oils (Photo 5).

Recipe Tip

Rub the lemon zest into the sugar. This small step helps release the natural oils from the lemon zest and noticeably improves the citrus flavor in the filling.

Step 7: Whisk in the cornstarch, then add the eggs and egg yolks and whisk until smooth without whipping excess air into the mixture. Whisk in the lemon juice until fully combined (Photo 6).

Step 8: Place the saucepan over medium-low heat. Switch to a silicone spatula and cook while stirring constantly, scraping the bottom and sides of the pan to prevent the eggs from scrambling (Photo 7). Cook until the curd thickens and reaches about 160°F on an instant-read thermometer, which usually takes about 8–12 minutes.

Step 9: Immediately remove the pan from the heat and pour the curd through the prepared strainer over the cold butter (Photo 8). Let it sit for about 30 seconds, then gently stir until the butter is melted and the curd is smooth and glossy.

Collage of four photos showing steps 9-12 for how to make sourdough lemon bars.

Step 10: Pour the warm lemon curd over the baked crust and gently tap the pan on the counter to release any air bubbles (Photo 9). Return the pan to the oven and bake at 325°F for 12–16 minutes, until the edges are set and the center of the lemon bars jiggles like firm gelatin when gently shaken (Photo 10). The center may still look slightly loose, but it will finish setting as the bars cool.

Step 11: Allow the bars to cool at room temperature for about 1 hour, then transfer them to the refrigerator and chill for at least 4 hours, preferably overnight. Once fully chilled, lift the bars out of the pan using the parchment paper and cut into 9 thick bakery-style bars or 12–16 smaller bars (Photo 11). Dust with powdered sugar just before serving if desired (Photo 12). These bars are best served chilled.

Sourdough lemon bars cut into squares and dusted with powdered sugar.

Recipe Tip

Powdered sugar is optional but traditional. Dust the bars lightly just before serving so the sugar doesn’t dissolve into the lemon layer.

How to Store

Store lemon bars in an airtight container in the refrigerator for up to 4 days. They taste best served chilled.

Make-Ahead Instructions

These bars are great for making ahead. In fact, the flavor and texture often improve after several hours in the refrigerator, making them a perfect dessert to prepare the day before serving.

Sourdough Lemon Bars Tips

Use an instant-read thermometer for the lemon curd. Cooking the curd to about 160°F ensures the eggs thicken properly without scrambling. A thermometer takes the guesswork out of this step and helps create a smooth, glossy lemon layer.
Don’t worry if the center still jiggles slightly after baking. The lemon filling should jiggle gently when the pan is shaken, similar to soft gelatin. The bars will continue to set as they cool and will firm up completely once chilled.
Allow the crust to lightly brown for the best flavor. Baking the crust until the edges are lightly golden helps develop a richer shortbread flavor. If the crust looks very pale, it likely needs another minute or two in the oven.
If the crust becomes warm while pressing it into the pan, you can refrigerate the pan for about 10 minutes before baking. This helps the butter firm up and encourages a more even bake.
The crust does not need to stay piping hot before adding the filling. It can sit at room temperature for 10–20 minutes while the lemon curd is prepared.
For the cleanest slices, chill the bars well before cutting. Refrigerating the bars for at least 4 hours, or overnight, allows the lemon curd to fully set and makes it much easier to cut neat bakery-style squares.
Regular lemons can be used if Meyer lemons are not available. Meyer lemons are slightly sweeter and less tart, but standard lemons work perfectly well and will simply produce a brighter, tangier flavor.

Recipe FAQs

Can I make these lemon bars without sourdough discard?

Yes. Replace the ½ cup sourdough discard with ¼ cup sour cream or plain yogurt and reduce the flour by about 2 tablespoons. The crust will still be tender and flavorful.

Can I use regular lemons instead of Meyer lemons?

Yes. Regular lemons work perfectly well and will give the bars a slightly brighter, more tart lemon flavor compared to Meyer lemons, which are naturally sweeter.

Why does the center still jiggle when the bars come out of the oven?

This is normal. The lemon curd continues to set as it cools and firms up completely after chilling in the refrigerator.

How long should the bars chill before cutting?

For the cleanest slices, refrigerate the bars for at least 4 hours. Overnight chilling is even better and allows the filling to fully set.