Oh, *that's* what key lime pie was missing

Every week in Genius Recipes—often with your help!—Food52 Founding Editor and lifelong Genius-hunter Kristen Miglore is unearthing recipes that will change the way you cook.

* * *

Seeing a pie topped with a spectacular, toasty-tipped coif of meringue, your first reaction might be: That looks stunning! I would really like…someone else to make it for me. (It's definitely mine.)

Meringue pies are mercurial. Meringue pies have rules. Meringue pies are just waiting for you to dedicate a chunk of your day to making a crust and a curd and a fluff, only to see them slowly self-destruct before dinnertime. Or emerge so cloying you abandon your slice for more Ranch Fun Dip instead.

But not Petra Paredez's meringue pie. It comes equipped with a meringue you won't undercook or overwhip, a curd that balances the creamy sweet with floral tang, and—maybe most memorably—the subtle-but-emphatic power of more salt than you think should be there.

After tasting the pie from Petee's Pie Company, where Petra is the co-owner and head baker, our co-founder Amanda Hesser sent it my way. "There were no frills—just thoughtful layering of flavor," Amanda wrote. "Delicious lime curd, not too sweet. And it was topped with a salty—salty!—meringue that was arranged in swirls and lightly toasted. I thought the salty-sweet thing was GENIUS."

And that was before she knew how simple it is to make at home.

As Petra told me, "The challenge for me was just to make something that was as good as my dad's—and then make it different." Her dad's are sold frozen, also swirled with meringue, at her parents' business—Mom's Apple Pie Company in Leesburg, Virginia—where Petra learned how to make and sell great pies.

Like most Key lime pies, the creamy middle in Petra's is as simple as whisking together sweetened condensed milk, egg yolks, and lime juice and zest. But Petra skews hers tart rather than sweet, adding extra lime juice and just enough extra egg yolks to help the curd set. She's tried Key limes and grocery-store Persian limes, and while both will work, the latter are her favorite. "Perhaps another unpopular opinion, but, yes, I think Persian limes are just as good," she told me. "And super tasty and less of a pain in the neck to get a lot of juice out of."(1)

Petra goes with an Italian meringue (egg whites whipped with a hot sugar syrup)—which is more forgiving and stable than French (whipped with not-hot sugar) and Swiss (heated over a double boiler with sugar, then whipped), and is cooked through before it even blops onto the pie. Even if you think you've messed it up—in the video above, I actually did a little, letting my fear of overwhipping keep me from full billowing floof—it will be edible and, in fact, delicious.

And you really don't need to worry about overwhipping it. Petra has discovered that it can rebound, if you just give it a little time. "If you find that you've gotten to the point where it's beyond stiff peaks and it's a harder foam," she told me, "Just chill, have a glass of wine, and then re-whip it afterwards and find that all is not lost."

Far from lost, the salty-sweet meringue will keep tugging you forward. And you—not some future someone—will want to make it again and again.

Key Lime Meringue Pie From Petra Paredez

Prep time: 4 hours 30 minutes
Cook time: 30 minutes
Makes: one 9-inch pie

Ingredients

Key Lime Meringue Pie

• 1 14-ounce (420-milliliter) can sweetened condensed milk
• 5 large egg yolks
• ¹/₂ cup plus 2 tablespoons (150 milliliters) freshly squeezed lime juice, from about 7 Persian limes, or about 15 Key limes
• Zest of ½ Persian lime or 1 Key lime
• 1 par-baked crust of your choice—see Author Notes

Vanilla Sea Salt Meringue

• ¹/₂ cup (120 milliliters) egg whites (equivalent of 3 large egg whites), at room temperature
• ¹/₂ teaspoon cream of tartar
• 1 cup (200 grams) sugar
• ¹/₂ teaspoon pure vanilla extract
• ¹/₄ teaspoon fine sea salt

Directions

Key Lime Meringue Pie

1. Heat the oven to 350°F (175°C). 
2. In a large bowl, whisk together the sweetened condensed milk and egg yolks. Add the lime juice and whisk until smooth. Whisk in the lime zest.
3. Pour the filling into the par-baked crust, making sure to scrape the entire contents from the sides of the bowl into the pie. Bake until the outer edges of the pie have solidified, but the center of the pie looks slightly fluid under the surface when the pie is jiggled, 15 to 20 minutes.
4. Meanwhile, make the meringue (see below).
5. When the filling is done, pile the meringue on top of the pie, making sure the meringue touches the inner edge of the crust, not just the curd, to prevent sliding. Use the back of a hot, wet spoon to create a wavy texture with peaks and valleys, or transfer the meringue to a pastry bag fitted with a fluted tip and pipe it on, starting at the outer edge and working your way to the center.
6. Set the oven rack so that when the pie is on it, the very top of the pie is 3 to 5 inches (7½ to 12 centimeters) from the heating element. Set the pie on a baking sheet so you can move it in the oven more easily.
7. Turn the broiler on high. When the heat is in full effect, place the pie under the broiler and set a timer for 1 minute. Broiler heat varies wildly from oven to oven, so keep a close eye on the pie for the entire time it is under the broiler, carefully rotating the baking sheet if needed to toast the meringue evenly. Heat until the peaks of the meringue turn golden brown, anywhere from 1 to 3 minutes, depending on your oven.
8. Transfer the pie to the fridge until cooled completely, about 4 hours. To serve, slice with a hot, wet knife in order to avoid dragging the meringue. The pie will keep for up to 5 days, covered, in the fridge. 

Vanilla Sea Salt Meringue

1. Make sure the egg whites are completely free of any yolk and that your bowl and mixer attachments are completely clean and non-greasy. Otherwise, the egg whites will not whip properly.
2. In the bowl of a stand mixer with the whisk attachment or in a large bowl with a hand-held mixer, beat the egg whites and cream of tartar on high until they are white and foamy and hold soft peaks.
3. Meanwhile, in a saucepan, stir ¼ cup (60 milliliters) water and the sugar over high heat until the sugar has dissolved and the syrup reaches a strong boil. The temperature on a candy thermometer should read 240°F (116°C) (this is the soft ball stage—if you carefully drip a little syrup into a glass of cold water, it will form a soft, malleable ball). Remove from the heat.
4. With the mixer running, pour the hot sugar syrup in a thin stream into the foamy egg whites. Continue beating until the meringue holds the pattern of the whisk or beater as it spins. The texture should be voluminous but still silky. If it is looking fluid and sticky, feel free to keep beating until it firms up. (Even if you overwhip it, it can be saved—see Author Notes.)
5. Add the vanilla and salt and beat just until combined.
6. Use the meringue immediately to assemble a meringue pie according to the instructions in the recipe, or use as a pie sundae topping.

(1) For more about why the Key limes available to most of us aren't what they used to be, see this informative rant from Stella Parks over on Serious Eats.