Preserved lemon is next on the list of savory seasonings about to take over mainstream sweets

Preserved lemon is one of those ingredients that, once it becomes a regular part of your cooking routine, it's nearly impossible to do without. Savory dishes like crunchy salad, oil-slicked pasta, and tender roast chicken all beg for a hit of tangy, salty preserved lemon. But what happens when, instead of stirring chopped preserved lemon into salad dressing or couscous, you fold it into cake batter? Magic, that's what.

To back up: Preserved lemon, or salted whole lemons fermented until soft, is typically used as a seasoning or condiment in Tunisian, Moroccan, Israeli, Iranian, Turkish, and other North African and Middle Eastern cuisines, as well in dishes around the Indian subcontinent, where it's known as lemon pickle, and is also seasoned with additional flavors like turmeric, chili powder, and cumin, among others, depending on the region. Chopped whole (yes, pith and peel, too) and seeded, preserved lemon can be stirred into nearly any dish that calls for fresh lemon, adding all the brightness of tart citrus with a bit more complexity. The brine, a deeply seasoned, lightly lemony syrup, should also be used in cooking, even after the lemons are gone.

A hint of lemon in baked goods like vanilla cakes and sugar cookies is so common, I've sometimes found myself zesting the fruit before even reading through a full ingredient list (not recommended!). Lemon adds a fresh tang to sweet treats, even when it's not the main flavor; preserved lemon is simply a punchier version of its fresh counterpart. Just imagine your favorite pound cake, cheesecake, ice cream or custard pie with the zing of fresh lemon, as well as the subtly salty funk that comes with fermented condiments.

Savory ingredients cropping up in dessert is nothing new, but they continue to delight, from where I'm baking. For a while, it was all about tahini: The relatively mild sesame paste isn't that different from unsalted peanut butter, and has been a recurring guest star in baked goods for years. I've seen cookies and pound cake imbued with earthy miso paste, salty fish sauce caramel rippled through ice cream, and tangy sumac popping up in brownie cookies and olive oil cake. Odds are you've seen Chinese five spice or chili powder make an appearance in a treat or two recently, and of course, it would appear as though Big Cardamom is running a campaign to replace cinnamon in every bun, cake, and cookie it can get its hands on these past few years in the U.S. I'm here to predict that preserved lemon is next on the list of savory seasonings about to take over mainstream sweets.

When it comes to actually putting preserved lemon in a bake, give yourself room to experiment, but a great place to start is with recipes that already call for fresh lemon (or another citrus) juice. Of course, there is a texture difference between finely chopped preserved lemon and juice, but it typically won't make a major difference in cakes or custards. You may want to add a bit of extra fresh lemon juice in addition to the preserved in instances where lemon is the star of whatever you're baking, as well as reduce the salt called for in the recipe by three quarters, or even entirely (as I did in this filling for these preserved lemon bars,) but for the most part, consider a one-to-one swap.

While you can make your own preserved lemon, I am lazy, and store-bought really is fine. Available most typically in its whole-lemon form (my favorite brands are Mina and Tara Kitchen), you can also find preserved lemon paste (for that, I love New York Shuk, as well as the less regularly available preserved Meyer lemon paste from small-batch vinegar company Tart), which is already seedless and mostly smooth — ideal for baking.

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Recipe: Salty-Tangy Preserved Lemon Bars

Prep time: 15 minutes
Cook time: 30 minutes
Makes: 16 squares (or 32 smaller triangles)

Ingredients:

Crust

• 1 3/4 cups (225 grams) all-purpose flour
• 1/4 cup (50 grams) granulated sugar
• 1/4 teaspoon kosher salt
• 10 tablespoons (1 stick plus 2 tablespoons) unsalted butter, cut into cubes (remove from fridge 10-20 minutes before baking)

Filling

• 1/4 cup (70 grams) preserved lemon paste (or 1/4 cup of seeded, puréed whole preserved lemons)
• 2 tablespoons lemon zest (from about 2 lemons)
• 6 tablespoons fresh lemon juice (from about 2 lemons)
• 2 large eggs
• 2 large egg yolks
• 3/4 cup (150 grams) granulated sugar
• 3 tablespoons (25 grams) all-purpose flour
• Powdered sugar, for serving (optional)
• Flaky salt, for serving (optional)

Directions:

1. Heat the oven to 325ºF and line an 8x8-inch square baking pan with parchment paper, leaving an overhang on all sides. (Save parchment paper by cutting one sheet several inches larger than the pan, cutting a slit in each corner, then pressing the paper into the pan.)
2. In a medium bowl, use your fingers to combine the flour, sugar, and salt, then work in the butter pieces with your fingers, until it forms into a crumbly mass. It may not all stick together, but if you can press together a handful and it holds its shape, you're good to go. Dump the dough into the prepared pan and hang onto the bowl.
3. Firmly press the dough into the pan in an even layer. Use a fork to prick holes over the entire surface. Bake until the shortbread is lightly golden brown, 20 to 25 minutes.
4. Meanwhile, make the filling: Place the preserved lemon paste, lemon zest and juice, whole eggs and egg yolk, sugar, and flour in the reserved bowl and whisk furiously until totally smooth.
5. Reduce the oven temperature to 300ºF. Pull out the oven rack the crust is baking on, and carefully pour the filling over the crust. Gently push the oven rack back and bake until the filling is set and just barely jiggles in the center, about 20 minutes.
6. Let the pan cool to room temperature, then transfer to the refrigerator to cool completely, at least 3 hours, but overnight is best for a clean cut. 
7. Pull out the bars from the pan by the parchment overhang, place on a cutting board, and slice into 16 squares (or 32 triangles). Dust with powdered sugar and sprinkle over flaky salt (if using).