Sourdough Lemon Bars Recipe

Yield

24 bars

Prep Time

30 minutes

Bake Time

45 minutes

Chill Time

3 hours

Total Time

4 hours 15 minutes

Ingredients

For the Buttery Shortbread Crust

• 2 cups (250g) all-purpose flour
• 1 cup (227g) unsalted butter, softened
• ½ cup (100g) granulated sugar
• ½ teaspoon salt
• 1 teaspoon pure vanilla extract

For the Sourdough Lemon Filling

• 1 cup (240g) sourdough discard (100% hydration)
• 1½ cups (300g) granulated sugar
• 5 large eggs, room temperature
• ¾ cup freshly squeezed lemon juice
• 2 tablespoons finely grated lemon zest
• ¼ cup (30g) all-purpose flour
• ¼ teaspoon salt
• 1 teaspoon vanilla extract

Optional Topping

• Powdered sugar for dusting
• Extra lemon zest
• Fresh berries for garnish

Equipment Needed

• 9×13-inch baking pan
• Parchment paper
• Mixing bowls
• Hand mixer or stand mixer
• Fine grater or zester
• Citrus juicer
• Whisk
• Cooling rack

Why Add Sourdough Discard?

Sourdough discard adds a subtle tangy note that complements the tartness of fresh lemons beautifully. It also creates a smoother, more custard-like texture in the filling. Rather than throwing away excess starter during feeding, this recipe transforms it into a gourmet dessert.

Benefits include:

• Reduces food waste
• Adds complexity of flavor
• Creates a creamier texture
• Balances sweetness naturally
• Makes traditional lemon bars even more flavorful

Step-by-Step Instructions

Step 1: Prepare the Baking Pan

Preheat your oven to 350°F (175°C).

Line a 9×13-inch baking pan with parchment paper, allowing excess paper to hang over the sides. This makes it easy to lift the bars out after chilling.

Lightly grease any exposed areas of the pan.

Set aside.

Step 2: Make the Shortbread Crust

In a large mixing bowl, cream together:

• Softened butter
• Granulated sugar

Beat for 2–3 minutes until light and fluffy.

Add:

• Vanilla extract

Mix until incorporated.

Gradually add:

• Flour
• Salt

Mix on low speed until a soft crumbly dough forms.

The dough may appear slightly dry at first, but continue mixing until it comes together when pressed between your fingers.

Transfer the dough into the prepared baking pan.

Using clean hands or the bottom of a measuring cup, press the dough evenly into the pan.

Take your time to ensure an even thickness across the entire surface.

Step 3: Pre-Bake the Crust

Place the crust in the preheated oven.

Bake for:

18–22 minutes

The edges should be lightly golden while the center remains pale.

Avoid over-baking, as the crust will return to the oven with the filling.

Remove from the oven and allow to cool slightly while preparing the filling.

Reduce oven temperature to:

325°F (163°C)

Step 4: Prepare Fresh Lemons

Wash and dry the lemons thoroughly.

Using a fine grater, zest enough lemons to obtain:

2 tablespoons lemon zest

Then juice the lemons until you have:

¾ cup fresh lemon juice

Strain the juice to remove seeds and excess pulp.

Fresh lemon juice makes a huge difference in flavor, so avoid bottled juice whenever possible.

Step 5: Make the Sourdough Lemon Filling

In a large mixing bowl combine:

• Granulated sugar
• Flour
• Salt

Whisk together.

Add:

• Eggs

Whisk until smooth and fully combined.

Next add:

• Sourdough discard
• Lemon juice
• Lemon zest
• Vanilla extract

Continue whisking until the mixture becomes silky smooth and lump-free.

For an extra smooth filling, strain the mixture through a fine-mesh sieve.

Allow the filling to rest for 5 minutes to release trapped air bubbles.

Step 6: Fill the Crust

Pour the lemon mixture over the warm crust.

Tap the pan gently on the counter several times.

This removes air bubbles and helps create a smooth surface.

If any foam appears on top, skim it off with a spoon.

Step 7: Bake the Lemon Bars

Return the pan to the oven.

Bake at 325°F (163°C) for:

25–30 minutes

The filling should be set around the edges with only a slight wobble in the center.

Do not overbake.

The filling will continue to set as it cools.

Step 8: Cool Slowly

Place the pan on a wire cooling rack.

Allow the bars to cool at room temperature for approximately:

1 hour

Avoid placing hot lemon bars directly into the refrigerator because sudden temperature changes can cause cracking.

Step 9: Chill Completely

Transfer the cooled pan to the refrigerator.

Chill for at least:

3 hours

For best results, chill overnight.

This allows the filling to firm up and develop its full flavor.

Step 10: Slice and Serve

Using the parchment paper, carefully lift the bars from the pan.

Place on a cutting board.

Dust generously with powdered sugar.

Using a sharp knife, cut into squares or rectangles.

For professional-looking slices:

• Wipe the knife clean between cuts.
• Chill the bars thoroughly before slicing.
• Use a long, sharp chef’s knife.

Expert Tips for Perfect Lemon Bars

Use Room Temperature Eggs

Room temperature eggs blend more easily into the filling and create a smoother texture.

Don’t Skip the Chill Time

Proper chilling ensures clean slices and the perfect custard consistency.

Weigh Ingredients

Using a kitchen scale provides the most accurate results.

Use Fresh Citrus

Fresh lemons provide brighter flavor and aroma than bottled juice.

Avoid Overbaking

Overbaked lemon bars can become rubbery rather than creamy.

Delicious Variations

Raspberry Sourdough Lemon Bars

Swirl ½ cup raspberry puree into the filling before baking.

Blueberry Lemon Bars

Fold 1 cup fresh blueberries into the filling.

Meyer Lemon Bars

Replace regular lemons with Meyer lemons for a sweeter flavor.

Coconut Lemon Bars

Add 1 cup shredded coconut to the crust.

Lavender Lemon Bars

Mix 1 teaspoon culinary lavender into the sugar before preparing the filling.

Lime Bars

Substitute fresh lime juice and zest for a tropical twist.

Storage Instructions

Refrigerator

Store in an airtight container for up to 5 days.

Freezer

Wrap individual bars tightly and freeze for up to 3 months.

Thaw overnight in the refrigerator before serving.

Nutrition Information (Approximate Per Bar)

• Calories: 220
• Carbohydrates: 29g
• Protein: 3g
• Fat: 11g
• Saturated Fat: 7g
• Sugar: 20g
• Fiber: 1g
• Sodium: 95mg

Final Thoughts

These Sourdough Lemon Bars are the perfect combination of buttery shortbread and bright citrus flavor. The addition of sourdough discard transforms an already classic dessert into something uniquely flavorful, with a subtle tang that beautifully complements the lemons. Easy enough for beginner bakers yet impressive enough for special occasions, this recipe is a wonderful way to make the most of your sourdough starter while creating a dessert everyone will love. Every bite is creamy, tangy, sweet, and utterly irresistible.