How to Make Sourdough Lemon Bars (They’re Sweet + Tart + Amazing)

Sourdough Lemon Bars are a unique twist on a classic dessert that will impress your guests at your next gathering or if you just want to indulge in a treat at home.

Make sure your ingredients, especially the eggs and butter, are at room temperature to achieve the smoothest filling and a crust that’s just right. A great sourdough recipe for dessert lovers.

A single sourdough lemon bar on a plate, heavily dusted with powdered sugar, showcasing the luscious yellow layer of lemon filling atop a crumbly crust. A single sourdough lemon bar on a plate, heavily dusted with powdered sugar, showcasing the luscious yellow layer of lemon filling atop a crumbly crust.

Sourdough Lemon Bars

Sweet and tart lemon bars with a sourdough discard shortbread crust.
Prep Time 20 minutes
Cook Time 45 minutes
Total Time 1 hour 25 minutes
Serving Size 24 bars

Ingredients 

For the Crust

  • 1 cup all-purpose flour
  • cup sugar
  • ½ cup unsalted butter cold and cubed
  • ½ cup sourdough discard

Lemon Filling

  • ½ teaspoon salt
  • cups sugar
  • 2 tablespoons cornstarch
  • ½ teaspoon salt
  • ¼ cup water
  • 5 egg yolks
  • 2 eggs
  • cups lemon juice freshly squeezed for best flavor
  • 1 lemon zest

Asssembly

  • Powdered sugar

Instructions 

  • Preheat your oven to 350°F (175°C). Line a 9×9 or 8×8 inch baking pan with parchment paper, or spry with cooking spray.
  • Mix flour, sugar, and a teaspoon of salt in a medium bowl. Cut in the butter with a fork, pantry cutter, or your fingers. Continue cutting in the butter until the mixture resembles coarse crumbs. Gently mix the sourdough and discard until it begins to come together. It will look like a pie dough.
    A mixing bowl with sourdough lemon bar crust mixture, where the ingredients are combined but still crumbly, ready for pressing into the pan.
  • Press evenly into the bottom of the prepared pan. Bake for 15-20 minutes until lightly golden. Remove and cool slightly.
  • Prepare the Lemon Mixture. In a medium saucepan, whisk together sugar, cornstarch, and 1/4 teaspoon of salt. Stir in the water, lemon juice, and lemon zest. Cook over medium-high heat, stirring frequently, until the mixture boils. Once the mixture reaches a boil, reduce the heat to low and let it simmer for 1 minute. The mixture should thicken considerably.
    Two side-by-side images of a lemon bar pan, the left one without the filling and the right one filled with smooth, bright yellow lemon custard.
  • In a small bowl, whisk egg yolks and eggs. Gradually whisk in about 1/2 cup of the hot sugar mixture to temper the egg yolks. This step prevents the eggs from cooking.
  • Pour the tempered egg yolks back into the saucepan. Bring the mixture to a gentle boil and continue cooking, stirring constantly, for 2 minutes. The filling should be thick and smooth.
  • Remove from heat. Add 2 tablespoons of butter and stir until fully incorporated.
  • Assemble. Pour the filling over the crust, spreading out to smooth if necessary.
  • Bake: Bake for 20-25 minutes or until the filling is set. Cool to room temperature, then chill for at least 2 hours.
    A pair of images showing the lemon filling's transformation during cooking, with the left image displaying the initial mixture and the right image showing the thickened, vibrant yellow filling after heat has been applied.
  • Finish. Dust with powdered sugar, cut into bars, and serve chilled.
    Overhead view of a baking pan with lemon bars, as powdered sugar is being sifted over them, adding a snowy layer of sweetness. Overhead view of a baking pan with lemon bars, as powdered sugar is being sifted over them, adding a snowy layer of sweetness.

Notes

Make sure your ingredients are at room temperature before you start mixing. This will make things a lot easier and smoother.
If you want a stronger lemon flavor in your recipe, you can always adjust the amount of lemon zest you add.
It’s also always a good idea to chill these thoroughly before cutting for cleaner cuts.

I’ve made these bars for family gatherings, potlucks, and just for myself when I need a little pick-me-up. Trust me, they never disappoint! They disappear faster than anything else on the table, and everyone always asks for the recipe. Even my kids, who are picky, can’t resist diving into these lemony treats. I’ve found that letting them dust their own pieces with a generous sprinkle of powdered sugar makes the experience even more fun.

A single sourdough lemon bar on a plate, heavily dusted with powdered sugar, showcasing the luscious yellow layer of lemon filling atop a crumbly crust. A single sourdough lemon bar on a plate, heavily dusted with powdered sugar, showcasing the luscious yellow layer of lemon filling atop a crumbly crust.

Lemon Bar Tips

  • Sourdough Discard Age: The age of your sourdough discard can impact the crust’s flavor. If you prefer a subtler sourdough taste, use a fresher discard. For a tangier kick, older discards work wonders.
  • Lemon Juice Quality: While the recipe specifies fresh lemon juice, the variety of lemon you choose can also affect the taste. Meyer lemons, for instance, are sweeter and less acidic than regular lemons, offering a different flavor profile.

Key Ingredients and Tools

  • Sourdough Discard. Find this in your own kitchen if you’re maintaining a sourdough starter; otherwise, a baking enthusiast friend might share some. It adds a delightful tang and depth to the crust, distinguishing these lemon bars from the classic version.
  • Fresh Lemons. Look for these in the produce section of your grocery store. Fresh lemon juice and zest are crucial for that vibrant, citrusy punch in the filling. Bottled juice won’t deliver the same fresh flavor.
  • Cornstarch. It’s available in the baking aisle and is used as a thickener for the lemon filling. Without it, your lemon bars won’t set properly, and you’ll have a runny mess. There’s no great substitute for its thickening power here without altering the texture.
Side view of a sourdough lemon bar on a plate, highlighting the distinct layers of powdered sugar, lemon filling, and crust with a soft-focus background.
  • 9×9 or 8×8 inch Baking Pan. This is crucial for achieving bars of the perfect thickness. A pan that’s too large will result in thin, overcooked bars, while one that’s too small will give you bars that are too thick and undercooked in the middle.
  • Parchment Paper. Lining your baking pan with parchment paper makes sure that the lemon bars can be easily removed after cooling. It also makes cleanup a breeze.
  • Medium Saucepan. Needed for cooking the lemon filling. A saucepan with a heavy bottom will help distribute heat evenly, preventing the filling from burning.
  • Whisk. A good whisk is essential for combining the filling ingredients smoothly and preventing lumps. It allows you to mix thoroughly, ensuring the sugar and cornstarch are well incorporated into the liquid.
  • Mixing Bowls. You’ll need two sizes: a larger one for preparing the crust and a smaller one for tempering the eggs for the lemon filling. Make sure they’re sturdy and easy to handle.
  • Zester and Juicer. To get the most flavor out of your lemons, you’ll need a zester for the zest and a juicer to extract all the juice efficiently. Fresh zest and juice make all the difference in flavor.

Serving Suggestions

Serve with fresh berries and Vanilla ice cream, whipped cream, and mint tea

Troubleshooting and Help

Can I use bottled lemon juice instead of fresh?

Sure, you can use bottled lemon juice in a pinch, but honestly, fresh lemon juice will give you that bright, fresh flavor that bottled juice just can’t match. If you can, go for the fresh stuff!

What if I don’t have a 9×9 or 8×8 inch pan?

No worries! If you have a similar-sized pan, say a 7×11 inch, you can use that too. Just keep an eye on the baking time, as it might vary slightly. The goal is to get that perfect golden edge and set filling.

Can I make these lemon bars gluten-free?

Absolutely! Just swap out the all-purpose flour for your favorite gluten-free flour blend in the crust. Look for one that’s a 1:1 substitute to make things easy.

How long do these lemon bars keep?

They’ll stay fresh in the refrigerator for up to 5 days. Just make sure to keep them in an airtight container. They also freeze well if you want to save some for later. Just thaw overnight in the fridge before serving

Storing Leftovers

Refrigerating:

  1. Place the cooled bars in an airtight container. If you need to stack them, put a sheet of parchment paper between layers to prevent sticking.
  2. Store in the refrigerator for up to 5 days.

Freezing:

  1. Wrap each lemon bar individually in plastic wrap. This helps protect them from freezer burn and keeps them fresh.
  2. Place the wrapped bars into a freezer-safe bag or container. Seal it tightly to keep out air.
  3. Freeze for up to 3 months.

So, next time you’re in the mood for a refreshing and tangy treat, give these lemon bars a try.

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