Think warm temps with key lime pie

We’ve just returned from Key West where the temperatures weren’t quite up to Florida’s steamy standards, but it was certainly warmer than Delaware in a snowstorm. Since it was too cold to swim or snorkel, we spent our time exploring the museums and restaurants on the island. And at every turn, from Hemingway’s House (filled with six-toed cats) to the sunset pier, someone was selling a key lime concoction.

The bars on Duval Street offered key lime martinis, sundry shops featured key lime candies, delis boasted frozen key lime custard dipped in chocolate on a stick, and all the restaurants insisted they had the best, most authentic key lime pie. As you may imagine, we had to try several slices of pie to judge for ourselves.

For those of you unfamiliar with key limes, they’re not the same as the Persian limes you find in the grocery store. This tropical cultivar likely found its way to the Florida Keys with the Spanish in the 16th century, but very few key lime trees still survive in the area after groves were destroyed by hurricanes. Today, Mexico is the primary commercial source of key limes.

Key limes are smaller than their Persian cousins, about the size of a golf ball, and almost perfectly round with bright yellow flesh. Their thin rinds are pale green to yellow, sometimes with brown splotches. The tart, sharp taste of a key lime is memorable and unmistakable.

Which brings us to the origins of key lime pie. If you visit the Curry Mansion Inn, you’ll be told that a family cook known as Aunt Sally invented the creamy pie, but it’s more likely she learned the dish from the local sponge fishermen. Until the Overseas Highway was opened in 1930, there wasn’t any fresh milk or ice and no refrigeration; residents relied on canned condensed milk.

The most plausible theory of the pie is that a creative sponge fisherman either accidentally or deliberately combined key lime juice with sweetened condensed milk and watched the mixture thicken as the acidic juice curdled the milk. One taste of the smooth, creamy sweetness would be enough to convince him to re-create and refine his invention.

And the refinements continue to this day. There’s great debate over the correct way to assemble a key lime pie, starting with the crust. Most modern recipes call for a graham cracker crust; early versions probably used cream crackers (like the now-discontinued Uneeda biscuit) or a pastry crust. In addition to key lime juice, the filling can include egg yolks, cream cheese, heavy cream, sour cream or some combination thereof.

Because key lime juice is so acidic, baking the pie has become optional (although not in my kitchen; I prefer it spend 15 minutes in the oven). Toppings can vary from whipped cream to sweetened sour cream to meringue (not surprising since the filling uses 4 egg yolks). The one signature feature of key lime pie is its light yellow color. Adding green food coloring is absolutely out of the question.

Now that you’ve heard some of the options (I failed to mention the versions that call for frozen dessert topping), how do you choose which approach to take? In order to provide some test results, we followed the recipe on the bottle of Nellie & Joe’s Key West Lime Juice, the yellow bottle sold in souvenir shops from the waterfront to the airport in Key West, as well as our local Delmarva supermarkets. The pie was fine, nice texture and quite sweet, but a bit bland and without the punch of key lime flavor we expected.

A second attempt with a few tweaks - a little more key lime juice, one whipped egg white and some sour cream - that’s the taste we remembered. The slice of pie in the picture had the ideal balance of creamy and sharp with the bright kick of key lime. A homemade graham cracker crust added to the rich texture and flavor. I’ve included both of the recipes we tried, and there are hundreds of internet sites with claims of authentic and original recipes. If you’d prefer not to bake your own pie, you can always order one online, although it’s a bit costly: $39 for the pie and $42 for shipping direct from sunny Key West.

Nellie & Joe’s Key Lime Pie

9-inch graham cracker pie shell
4 egg yolks
14-oz can sweetened condensed milk
4 oz key lime juice

Preheat oven to 350 F. Bake pie shell until golden, about 10 minutes; cool to room temperature. In a mixing bowl, whisk together egg yolks and condensed milk until smooth. Add key lime juice and stir just until combined. Pour filling into crust and bake for 15 minutes. Cool on a rack for 10 minutes, then refrigerate for at least 3 hours. Garnish with whipped cream and lime slices.

Graham Cracker Crust

6 T butter, melted
1 1/4 C finely ground graham cracker crumbs
2 T confectioners sugar

Preheat oven to 250 F. Coat the inside of a pie pan with nonstick cooking spray; set aside. Combine all the ingredients in a mixing bowl and stir until all the crumbs are moistened. Using your fingers, press the crumb mixture evenly across the bottom of the pan and up the sides. Chill for 20 minutes before baking or filling.

Key Lime Pie

9-inch graham cracker pie shell
1 egg white
4 egg yolks
14-oz can sweetened condensed milk
1/2 C sour cream
1 t grated key lime zest
3/4 C key lime juice

Preheat oven to 375 F. Bake pie shell until golden, about 8 minutes; cool to room temperature. In a mixing bowl, beat egg white until soft peaks form. Add egg yolks, condensed milk and sour cream; whisk until smooth. Add key lime zest and juice; stir just until combined. Pour filling into crust and bake for 15 minutes. Cool on a rack for 10 minutes, then refrigerate for at least 3 hours. Garnish with whipped cream and lime slices.