The perfect sourdough lemon bars have a still crisp, buttery crust that almost melts into a sweet and zesty filling. Real lemon juice, loads of lemon zest, a few eggs, sugar and a little sourdough starter are baked until just set. Lemon bars are bright and full of flavor despite consisting of only a few good ingredients.
Sourdough lemon bars are the ideal year-round dessert. In winter or summer, they can brighten up both holiday and picnic tables alike. Real lemon desserts are such a satisfying sweet experience because of the tart complexity they bring. Using sourdough starter in the crust and filling reinforces that tang in a deliciously complex way. The key to this recipe is to not over-thicken the filling with an excessive amount of additional flour or cornstarch and to not over-bake the filling either. This recipe is a sourdough version of my classic Lemon Bars, which are just as scrumptious!
WHY YOU WILL LOVE SOURDOUGH LEMON BARS
- -LOTS OF TANG: This recipe calls for the zest of the lemons used to make the juice. Why waste a good lemon after juicing it when there is zest to be had?! The zest is where the flavor is and this version really packs a punch. The zest is first pulsed into the sugar before the remaining filling ingredients are added which helps coax out as much flavor as possible. Sourdough starter is then used to thicken the filling instead of just flour, which adds an extra layer of tang without being overly vinegar-like.
- –FEW INGREDIENTS: The primary ingredients in this recipe are flour, sourdough starter (which is just flour and water!), sugar, butter, lemons and eggs. Such a simple dessert with oh so much flavor!
- –MAKE THEM AHEAD: The beauty of this recipe is in the flexibility. The dough that forms the crust of the lemon bars can be made ahead and kept in the refrigerator or freezer. The filling can be made a head and kept in the refrigerator. In fact, making ahead makes these bars even more of a fermented dessert! And once the bars are baked, they keep well in the refrigerator for up to a week. Although in my experience they barely last 48 hours!
- -FOOD PROCESSOR DOES THE WORK: The dough for the crust of this recipe easily comes together in a food processor. After the dough is removed, the bowl can be wiped out and used again to make the filling!
- –POWDERED SUGAR WON’T MELT! Using my trick for “non-melting” powdered sugar, you can bring these lemon bars to a gathering without worrying that the beautiful topping will disappear completely by the time your guests are ready to enjoy them.
HOW THIS RECIPE COMES TOGETHER
- First, make the short crust. In the bowl of a food processor fitted with a blade, the flour, sugar, sourdough starter and cold, cubed butter are combined to form the dough. The dough is then pressed into a lined and greased 8 x 8 square pan and par-baked to form the crust.
- Next, make the filling. As the crusts cools, you can make the filling by using the food processor once more. Begin by pulsing the sugar and lemon zest together. This breaks down the zest and brings out the flavor. Finally, the starter, eggs and lemon juice are added and blended into a smooth mixture.
- Finally, bake! The filling is then poured over the cooled crust and baked again until just set. Cool the bars completely, top with “non-melting” powdered sugar and serve!
WHY SOURDOUGH STARTER IN A LEMON BAR?
It might seem strange or unappealing to incorporate sourdough starter into a lemon bar. I assure you, lemon bars are actually the perfect recipe for using sourdough starter or discard. The sourdough starter in this recipe does two things for the lemon bars:
- 1. Sourdough starter acts as a binder in the short crust and a thickener in the lemon bar filling.
- 2. Sourdough starter reinforces the tang of the lemon without overpowering it!
If you love using sourdough in sweet recipes, be sure to try my Easy One Bowl Sourdough Brownies and check out my tutorial for How To Make Sourdough Pie Dough.
MY FAVORITE SOURDOUGH RESOURCES
- 1. For beginners: I have been following Bonnie Ohara of Alchemy Bread for years, even before I got into sourdough. Her books are fantastic resources.
- 2. For shaping videos: I appreciate the detail and professionalism of the shaping technique videos from Maurizio Leo’s The Perfect Loaf. He also goes into detail about the science behind sourdough.
- 3. For recipes and more: Amy Bakes Bread is a wonderful online resource with a variety of creative sourdough recipes and lots of information.
- 4. For same day sourdough recipes: Country Roads Sourdough is my favorite go-to for simple, delicious sourdough recipes that can easily be made in a single day.
Sourdough Lemon Bars
A recipe for classic lemon bars made with sourdough starter in the crust and the filling!
Equipment
- 1 food processor
- 1 microplane
- 1 handheld or electric juicer
- 1 small strainer/sifter
- 1 8 x 8 square baking pan
- parchment paper
Ingredients
For the shortcrust
- 3/4 cup (94 grams) all purpose flour
- 1/4 cup (50 grams) granulated sugar
- 1/4 cup (60 grams) sourdough starter at peak, past peak or discard
- 3/4 cup (85 grams) salted butter cold and cubed
For the filling
- 2 cups (400 grams) granulated sugar
- 1/4 cup (60 grams) sourdough starter at peak, past peak or discard
- 6 extra large eggs
- 3/4 cup (180 ml) fresh lemon juice from 3 large or 5 small lemons
- zest of lemons used
For topping (optional)
- 1 tbsp powdered sugar
- 1 tsp corn or potato starch
Instructions
To make the shortcrust
- Line an 8 x 8 square pan with parchment paper and grease it so the bars are easier to remove after baking.
- In the bowl of a food processor fitted with a blade, combine the flour, sugar, sourdough starter and cubed, cold butter. Process the ingredients until they combine into a dough.
- Transfer the short dough to the greased pan and press it evenly into the bottom to form the crust of the lemon bars. At this point you can proceed with par-baking or chill the dough for future use.
Pre-bake the short crust
- Preheat a conventional oven to 350 degrees F.
- If the dough is still relatively cold after pressing into the pan, proceed with baking. If the dough is warm, let it chill in the refrigerator for about 30 minutes before baking. Bake the short dough on the center rack of the preheated oven for 15-20 minutes until the crust is just barely brown. Remove from the oven and let cool.
Make the filling
- In the bowl of a food processor fitted with a blade, combine the sugar and lemon zest. Lock the lid and pulse until the zest is just visible in little flecks. Open the lid and add the sourdough starter, eggs and lemon juice. Lock the lid again and process until smooth. Remove the blade and rap the food processor bowl on the counter a few times to expel some air bubbles from the filling.
- When the crust is cool, pour the filling on top.
Bake the bars
- Bake the lemon bars for 18-20 minutes on the center rack of the preheated oven until *just* set. Remove and let cool.
Finish the bars
- The bars are best after being chilled for at least 3 hours. You can top them simply with powdered sugar. To ensure the powdered sugar doesn't melt quickly, mix 1 tablespoons of powdered sugar with 1 tsp of cornstarch before sifting over the bars.
Notes
To make ahead: Both the crust and the filling can be made ahead and kept in the refrigerator separately before baking. After baking, the bars can be wrapped and refrigerated for 5-7 days. Bars can be stored in a freezer safe bag or container for up to 3 months. I do not recommend freezing them with the powdered sugar on top.
