Sourdough Lemon Bars
My sourdough lemon bars are one of my most popular recipes on Foragers of Happiness. I sent a batch of these bars to my husband’s work. Multiple people said these were the best lemon bars they had ever had! Needless to say, there were no leftovers. I hope you enjoy these sourdough discard lemon bars as much as they did!
Lemon is one of my favorite flavors especially in the warmer seasons. I have so many lemon recipes like my lemon blueberry sourdough scones and my lemon shortbread cookies with lemon glaze. Whether it’s a picnic, a tea party, a baby shower, or a holiday like Easter or Mother’s Day, this bright and cheery flavor is sure to fit right in your menu. My sourdough lemon bars are a classic treat that I am so excited to share with you. This recipe is truly so delicious and easy to make. There is sourdough starter in both the crust and the filling but your friends and family will have no idea.
Why You Will Love these Sourdough Discard Lemon Bars
This lemon bar recipe is perfect for lemon lovers. They can be made start to finish in a couple of hours. They use a generous amount of sourdough discard. There is sourdough discard in both the crust and the filling! I love that the delicious buttery crust strikes the perfect balance with the lemon layer that sits on top. They are the perfect way to satisfy your sweet tooth without overwhelming sweetness or richness. I truly think these are the best lemon bars and I hope you do too!
I modified my classic shortbread cookie recipe to use as the base of these bars. The only difference I made to my original recipe is substituting confectioner’s sugar for the regular sugar. This substitution creates a delightfully light texture while maintaining a delicious buttery shortbread crust.
How to Use Sourdough Starter in Lemon Bars
The obvious place to use the sourdough starter is in the crust, but I also added it in the filling. Some recipes for classic lemon bars call for a small amount of flour and other liquids in the filling. As it turns out, these ingredients can easily be replaced with sourdough starter.
Ingredients and Substitutions
For the Shortbread Base
- Butter: We use unsalted butter but you can also use salted butter if desired. Reducing the salt in the recipe by half can help them not come out too salty.
- Sugar: We use powdered sugar (also known as confectioners sugar) for this recipe. This creates a lighter and fluffier texture. You can also substitute regular granulated sugar and it will still taste delicious. The texture will just be slightly coarser.
- Sourdough starter: You can use active starter or discard from the fridge. I recommend weighing the starter if you are using active sourdough starter. Active starter is less dense because of the air bubbles.
- Vanilla
- Salt
- Flour: You can use all purpose flour or bread flour for this recipe.
For the Lemon Filling
- Eggs: We need whole eggs for this recipe.
- Sugar: For the filling we use plain white sugar. I have not tested this recipe with any alternatives so I cannot recommend any substitutions.
- Sourdough starter
- Lemon zest
- Lemon Juice: You need LOTS of fresh lemons for this recipe to achieve that perfect lemon flavor. Depending on the size and juiciness of the lemons you will need anywhere from 4-8. I highly recommend fresh lemon juice in this recipe. This is because most bottled lemon juices contain extra ingredients and are made from concentrate. This can affect the flavor of the bars. If you want to mix it up a bit, you can use Meyer lemons in this recipe. Meyer lemon bars will be sweeter and less acidic.
- Salt
How to Make Sourdough Lemon Bars
Make the Crust
Step 1: Cream butter, sugar and lemon zest.
Step 2: Add starter, salt and vanilla.
Step 3: Add flour.
Step 4: Line a 9×13 inch baking pan with parchment paper for easy removal when the bars are finished baking.
Step 5: Press the dough into the base of the baking pan.
Step 6: Bake for 20-22 minutes or until the crust begins to turn golden brown.
Make the Lemon Curd Filling
Step 1: Whisk together all filling ingredients in a large bowl.
Step 2: When the crust is finished baking, whisk the lemon curd mixture again and pour over the crust.
Step 3: Bake for 20 minutes. Bake times may vary slightly so check for signs of doneness (not wet appearing and somewhat firm when gently touched).
Step 4: Allow to cool completely in the pan. The bars will cool faster if you place the pan on a wire rack.
Step 5: Remove from pan, sprinkle with powdered sugar, and cut into squares.
How to Make Ahead
I do not recommend making these bars more than 2 days ahead of time. Because the have an egg base, they do not last as long. The moisture in the filling can also make the crust soggy if stored for too long.
If you do make these bars ahead of time, store the bars in the fridge without the powdered sugar. When ready to serve, top them with the powdered sugar.
How to Store
Because these bars have an egg custard base, they need to be stored in the refrigerator. I recommend storing them in an airtight container or on a plate wrapped in plastic wrap. They are best if consumed within 2-3 days.
Should I Use a Metal Pan or Glass Pan?
I recommend using a metal pan for these bars. Glass pans retain more heat than metal. This results in uneven baking and over-cooked edges when a glass pan is used.
Why Did the Crust Float to the Top?
Occasionally, the crust from lemon bars can lift, resulting in the lemon filling pooling under the crust. To prevent this, pour the filling into the pan while the shortbread crust is still hot so it will set quicker. Also, make sure you pour the filling directly in the center rather than on an edge.
I hope you enjoyed this sourdough take on traditional lemon bars. If you did, will you please leave a star rating? I am always open to your feedback!
If you love sourdough, check out these other delicious sourdough recipes:
Sourdough Lemon Bars
Ingredients
For the Crust
- 1 cup unsalted butter
- ⅔ cup powdered sugar (confectioner's sugar)
- ⅓ cup sourdough starter active starter or unfed discard from the fridge
- 1 teaspoon vanilla extract
- 1 teaspoon salt
- 2¼ cup all purpose flour
For the Lemon Filling
- 6 large eggs
- 2 cups granulated sugar
- ½ cup sourdough starter
- 1 tablespoon lemon zest about 2-3 lemons
- 1 cup lemon juice 4-8 lemons depending on size
- ¼ teaspoon salt
Instructions
- Preheat oven to 350℉.
- Line a 9×13 inch baking dish with parchment paper. (The edges of the parchment paper should come up the sides of the pan on two opposite sides. This will let you lift the lemon bars easily from the pan after baking). Set aside.
- In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and powdered sugar on medium speed.
- Add the sourdough starter, salt and vanilla and mix until combined.
- Set the stand mixer to low speed and slowly add the flour. Mix until just fully combined.
- Press the dough evenly into the bottom of the prepared baking pan to form the bottom layer of crust.
- Bake the crust for 20-23 minutes or until starting to turn golden brown.
Prepare the Lemon Filling
- In a large bowl, whisk together the filling ingredients (eggs, sugar, sourdough starter, lemon zest, lemon juice, and salt) until smooth.
- Pour the mixture over the crust while still warm from the oven.
- Reduce heat in oven to 325℉.
- Bake the lemon bars for 20-23 minutes or until the mixture is just fully set. It should wobble but not appear wet when done.
- Allow to cool in pan completely at room temperature (about 45 minutes).
- Use parchment paper to gently lift the bars from the pan. Dust with extra powdered sugar through a mesh sieve.
- Cut the bars into approximate 2 inch squares and serve.
Made them!
Delicious! I did have to switch up because I didn’t have enough butter so about 80g of my fat was coconut oil. It was still very very delicious! Wow!
Thank you for the feedback! I’m glad to hear they worked out with the coconut oil as well!
Does the starter need to be active for both the filling and the crust or can I use discard for both?
You can use discard for both but it would work either way. I hope this helps!
Can these be frozen ?
Hi Brandi!
I haven’t tried it but I think the texture of the filling might get a bit weird in freezer.
I wanted to share an update from my last comment. These actually came out amazing in the end!! Yay!! Idk why the filling was so runny and ran out over the sides of the crust, but it ended up working. The filling all settled at the bottom of the pan. Once they were totally cooled, I lifted the parchment paper to pull the bars out of the pan. I flipped them and wouldn’t you know the filling had totally thickened on the bottom. They looked perfect and tasted sooo good!! The lemon flavor was the perfect balance is sweet and tart. Now that I figured it out I’ll be making again! So sorry for my confusion. 🤪
These were delicious!! So much better than from a box.