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The Secret to Real, Traditional Key Lime Pie

Christy learned the art and science of cooking from her Southern kin. Her cooking secrets aren't secrets because she shares them freely.

What’s the Key to Real Key Lime Pie?

Tucked away in our family recipe book is a yellowed page with the unevenly inked letters of an old manual typewriter. “KEY LIME PIE,” it says at the top of the page. And at the bottom:

“Grandmother got this when she lived in the Keys in the ’30s.”

That explains her answer to one of the most divisive key lime pie debates: cooked or not. When you live in the Florida Keys, notorious for long, hot summers, before electric refrigerators and certainly before air conditioning, you do not serve raw eggs. Full stop.

But after you nosh on this amazing-but-super-easy pie, read the rest of this page to learn some interesting things about key limes—starting with the fact that your key limes were probably not grown in the Keys. Or even in Florida.

Cook Time

Prep timeCook timeReady inYields

15 min

25 min

40 min

6 servings

Ingredients

  • 1 graham cracker crust
  • Key lime zest, for garnish (optional)

For the filling:

  • 1 (14-ounce) can sweetened condensed milk
  • 4 egg yolks
  • 1/2 cup key lime juice
  • 1 egg white

For the meringue:

  • 3 egg whites
  • 6 tablespoons sugar
  • 1/2 teaspoon cream of tartar

Instructions

  1. In a bowl, mix the condensed milk and lime juice; then add the egg yolks.
  2. In a separate bowl, beat 1 egg white until stiff, and then fold into the mixture of milk, lime juice, and egg yolks.
  3. Pour the batter into the graham cracker crust.
  4. Bake at 350°F for about 15 minutes, or until the filling is firm but slightly jiggly.
  5. While the pie is baking, make the meringue. Beat 3 egg whites and gradually add sugar and cream of tartar.
  6. Spread the meringue mixture over the baked pie and return it to the oven. Bake at 350°F for another 5 to 10 minutes, or until the meringue is set and the peaks just begin to brown. Do not overcook.
  7. Optionally, garnish with zest from the limes.

Substitutions

  • For the graham cracker crust: a pie shell
  • For key limes: Persian (green) limes
  • For the meringue: whipped cream

Is Real Key Lime Pie Baked or Not?

That’s the age-old question, isn’t it?

My grandmother baked her pie. She lived in the Keys in the early 1930s; by 1936 she was living in Tampa. And in the early 1930s, she wouldn’t have had an electric freezer or even a refrigerator. She did not serve raw eggs.

Even today, it can be dangerous to eat raw eggs. So, really, the question shouldn’t be whether to bake it or not.

The real question is, why wouldn’t you bake it, especially because this pie is so delicious?

Graham cracker crust

Graham cracker crust

Graham Cracker Crust or Baked Pie Shell?

This is another debate that’s as old as the recipe.

My grandmother’s recipe allows for either. Note, however, that I listed a graham cracker crust in the recipe. I guess that tells you which side of the debate I landed on. I think the sweetness of the graham cracker crust helps round out the tartness of the key limes.

The first known published recipe (read on) calls for a graham cracker crust. Some of you might say this settles the debate for authentic Key lime pie. But does it, really? My grandmother’s recipe allows for either, so maybe it’s only the one published recipe that doesn’t like choices.

If you want to maximize the tartness, go with a pie shell. See what you think. You should have a choice. Yay for freedom!

Fresh Limes or Bottled Juice?

Fresh key limes are best. You’ll get the richest flavor, without the possible metallic taste and the preservatives used in bottled juice.

That said, if you don’t have access to fresh key limes, there’s no shame in using bottled juice!

These days, I live in Minnesota. Key limes don’t show up in most of the grocery stores. I have to look for them in international grocery stores or settle for bottled juice.

If you can’t find fresh key limes or bottled key lime juice? That’s when you settle for the green stuff. (No, not dollar bills. Persian limes!)

Key limes on a Florida tree

Key limes on a Florida tree

What Are Key Limes? How Do Persian Limes Differ?

It’s a funny thing, the way our commercial food system works.

Key limes originated in Southeast Asia and eventually made their way to the West Indies and the Florida Keys, which is where we get our name for this little fruit. But commercial Florida citrus growers generally don’t raise them anymore. When you buy key limes, they’re probably imported from Mexico or South America.

Florida citrus growers raise Persian limes, which—you guessed it—are not from Persia.

Here’s the skinny:

Key Limes

Key limes, sometimes call Mexican limes or West Indies limes, are smaller and rounder than Persian limes. They’re acidic and tart. When they ripen, the rind turns from yellow, possibly with some green splotches. The juice is yellow. Thus, pie made from real key limes is yellow, not green.

They are also tarter than Persian limes, almost bitter, which is why they need to be balanced with other flavors. The sugar in the meringue does this perfectly. Key lime pie without meringue or whipped topping is quite bitter.

Persian (Green) Limes

Persian limes are larger, oval-shaped, and solid green. The skin is thicker, which makes it easier to ship them to grocery stores.

The juice is green. All those “key lime” pies you see that are green are either Persian lime pies or they’re dyed with food coloring. It’s the first giveaway that what you’re eating is not authentic key lime pie.

Why does it matter? Because Persian limes aren’t as aromatic and complex. They’re okay—use them if they’re what you have—but they’re an imperfect substitute for the authentic flavor profile of key limes.

Why Aren’t Key Limes Grown in the U.S.?

Because of a little thing called the Great Miami Hurricane of 1926.

They were prized as a regional crop in Florida, not only in the Keys, in the early 20th century. When the 1926 hurricane made landfall in Miami, it was probably a Category 4, using today’s scale. It ripped across the peninsula.

Around Lake Okeechobee, where my father went to high school, the surge breached the mud dikes and drowned hundreds of people. The town of Moore Haven was submerged under 13 to 15 feet of water. Needless to say, the precious key lime trees were wiped out.

Growers replaced most of the key lime groves with Persian limes, which had no thorns and were more disease-tolerant. The thicker skins also made it easier to transport the fruit.

Now, a few people have key lime trees in their backyards, and a few specialty growers might have small harvests, but most of our key limes come from Mexico or South America.

If you don’t see them at your grocery store, look for Mexican limes or West Indies limes. If you still can’t find them, try an international grocery store. (You should be going there anyway for your Thai chili peppers, jasmine rice, authentic curry paste, and a whole host of other wonderful international flavors.)

Where Does This Recipe Come From?

The irony is that, like today’s commercially grown key limes, the recipe probably doesn’t come from the Keys.

The first known publication was in the Miami Herald in 1933. Mrs. Mabel McClanahan’s recipe was titled “Tropical Chiffon Lime Pie,” nodding toward its original origins: it likely originated among local residents in the 1800s.

So is that where my grandmother got the recipe? Maybe she came across a Miami newspaper, or a paper in the Keys carried it subsequently. It’s the right timeframe.

Or maybe the locals taught her a recipe that was already spreading. There are various undocumented stories of a lime pie in South Florida before 1933.

My grandmother grew up in Southwest Georgia, where she certainly wouldn’t have learned this recipe. She began her travels across Florida when she married my grandfather, a Baptist preacher at little country churches all across the state.

Or maybe she later copied it from a cookbook and our family lore just attributed it to her time in the Keys.

All I know for sure is this: it’s one darned good pie!

The first thing to make with leftover key limes: margaritas!

The first thing to make with leftover key limes: margaritas!

10+ Ways to Use Leftover Limes

Well, the obvious answer is, the next key lime pie.

But if you want something different, try:

  • Margaritas
  • Key lime tarts
  • Key lime fudge
  • Coconut key lime cookies
  • Tilapia tossed in lime juice
  • Shrimp tossed in lime juice
  • Ceviche
  • Chimmichurri
  • Grilled corn with key lime butter
  • Coconut lime rice

And the list goes on. Try new things! Experiment! Enjoy!

© 2020 Christy Marie Kent

Comments

Christy Marie Kent (author) from Minneapolis, Minnesota on December 10, 2020:

Thanks for sharing, Peggy! Texas and Florida both have better access to Key limes than I do. I'm living in the frozen tundra of Minnesota now.

Peggy Woods from Houston, Texas on December 10, 2020:

The first time I ever ate key lime pie was in Florida. My aunt and uncle took my mother and me to a little island where we had dinner and finished the meal with key lime pie. It is delicious! Thanks for sharing the recipe and information about these types of limes. We can buy them at times in our grocery stores here in Houston.