Sourdough Lemon Bars Recipe

Yield: Bars

Prep Time: 10

Cook Time: 50

Total Time: 1

These Sourdough Lemon Bars are the perfect lemon bars, but now with a delicious twist! Zingy, bright, and tart lemon filling tops a sourdough shortbread crust that is light and buttery. The perfect sweet treat to brighten anyone's day.

4.53 from 34 votes

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Equipment

Ingredients

Sourdough Crust

170 grams unsalted butter, melted 3/4 cup
120 grams sourdough discard 1/2 cup
250 grams all-purpose flour 1 3/4 cups
60 grams powdered sugar 1/3 cup
pinch of salt

Lemon Filling

6 eggs beaten
425 grams sugar 2 cups + 2 Tablespoons
150 grams sourdough discard 1/2 cup + 2 Tablespoons
175 grams lemon juice, freshly squeezed 3/4 cup
zest of one lemon

Instructions

Preheat the oven to 350 degrees F. Prepare a 9x13 baking dish with parchment paper, leaving enough overhang for easy removal of the bar after baking for easy slicing. Set to the side.
In a medium bowl, add the melted butter and sourdough discard. Whisk until combined. Set aside.
170 grams unsalted butter, melted, 120 grams sourdough discard
In a separate bowl, whisk together the flour, powdered sugar and salt. Add the wet ingredients to the flour mixture and mix until it resembles pie dough.
250 grams all-purpose flour, 60 grams powdered sugar, pinch of salt
Pour the dough into the prepared baking dish and gently press the dough with your hands, trying to press everything as even as possible and to the edges! Bake for 25-30 minutes, or until the shortbread base is lightly golden brown.
I prefer a more crisp sourdough shortbread, so I tend to bake the full 30 minutes.
While the crust is baking, prepare the lemon layer.
In a large bowl, add the sugar and lemon zest. Rub the lemon zest and sugar in between your clean hands.
This helps to extract the lemon oils from the zest, giving these lemon bars even more delicious lemon flavor!
425 grams sugar, zest of one lemon
To the lemon sugar, add the sourdough discard and whisk until combined. Then add in the eggs and whisk until smooth. Finally pour in the freshly squeezed lemon juice and mix by hand until well-blended.
6 eggs, 150 grams sourdough discard, 175 grams lemon juice, freshly squeezed
Once the crust is baked, remove the pan from the oven. Poke the shortbread with the prongs of a fork all around its surface.
This helps the lemon custard to adhere to the sourdough shortbread.
Pour the wet ingredients over the hot base layer and return to the oven. Continue to bake for another 25-30 minutes or until the lemon filling has set and has the iternal temperature of 180 degrees F.
Remove the Sourdough Lemon Bars from the oven and place them on a wire rack to cool for at least an hour and then for two hours in the fridge for it to set. The chill time is crucial for allowing the filling to set and for easy slicing. Before serving, dust with powdered sugar, if desired. Slice and enjoy!

Notes

Ingredients You’ll Need

Sourdough Crust

Unsalted Butter – In order to create a buttery shortbread crust, you need butter! Use melted butter for easy mixing.
Powdered Sugar – Brings the perfect sweetness to the crust without any gritty texture.
Flour – All-purpose flour is what I used to make this tender crust.
Sourdough Discard – For sweeter recipes like these sourdough bars, I like to use 1–2-day-old discard. You can use active sourdough starter, just measure the same amount in grams.

Lemon Filling

Large Eggs – Brings structure to the lemon filling and helps it to set properly.
Sugar – The needed sweetness to balance the tartness from the lemon juice.
Sourdough Discard – This helps thicken the lemon curd! Just as before, use fresh sourdough discard or the same amount of active sourdough starter.
Lemon Juice – The star ingredient! That being said, I highly suggest using freshly squeezed lemon juice for the best lemon flavor. Don’t use lemon concentrate. I used regular lemons in this recipe, instead of others like Meyer lemons. You could also substitute the lemon juice for orange juice or lime juice instead!

FAQs:

Can I use bottled lemon juice instead of fresh for lemon bars?

Since lemon is the star ingredient of this recipe, you want to use real lemon juice. Lemon juice from a bottle or concentrate can be handy in a pinch, but for the best flavor, I highly recommend using freshly squeezed lemon juice.

Can I use active sourdough starter instead of discard?

Absolutely! Just be sure to use the same amount in grams.

Why are there small, white bubbles on top of my Sourdough Lemon Bars?

Bubbles forming on top of your Sourdough Lemon Bars is normal. These bubbles are from whisking the eggs. While baking, the bubbles will rise to the top of the lemon curd. These can, however, brown lightly while baking. Luckily they can be covered up nicely with powdered sugar.

This recipe card was updated on 03/22/26.

Nutrition

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