The Truth About Key Lime Pie

During a high school reunion (won’t say which one) I revisited my hometown of Miami, Florida and rediscovered an old flame of mine. It wasn't an ex-boyfriend - it was Key Lime pie. I had forgotten how perfect it was with it's contrasting sensations of sweet and tart, creamily dense but light and ethereal at the same time.  I was so truly taken with it I scouted my old restaurant haunts and a few new ones to find the perfect recipe for key lime pie. After making a nuisance of myself to the wait staff, and interrogating many Miami pastry chefs I came upon the realization that the true key lime pie filling is made up of only 3 ingredients - sweetened condensed milk, egg yolks, and fresh key lime juice.

Key limes are not native to Florida. They made a circuitous route to the keys by way of Malaysia to North Africa and the Near East. Their next stop was the Mediterranean and then on to Haiti. The Spanish introduced key limes to Florida where they flourished, especially in the keys. Hurricanes eventually wiped out the key lime trade in Florida. Now most key limes are imported from Mexico. Don't mistake the Persian lime we find at our local supermarkets for key limes. Key limes are thin skinned and are about half the size of Persian limes. They are very acidic when green but mellow as they ripen and yellow.

Like many other recipes, key lime pie was born out of necessity. The keys, a chain of small islands south of the Everglades in Florida was first colonized by the Spanish (remember Ponce de Leon) who introduced key limes to the area. Cows were not abundant in the keys nor did the milk keep. So it was a godsend when canned sweetened condensed milk was invented in 1859.

But it was the advent of sweetened condensed milk in 1859 that inspired this pie.

In  1856 canned sweetened condensed milk arrived in the keys. With the addition of egg yolks for thickening and lime juice for cooking the key lime quickly became a success. Although pie is served in a graham cracker crust the original crust was a pastry crust.

The original pie wasn't baked. How could you blame them? Would you want to stoke a hot oven in tropical Florida? So how does the pie thicken? The secret is the acidity of the limes. Acids, just like heat, denature proteins. 

Don’t be fooled by St. Patrick’s Day green colored key lime pies. A true key lime pie is a pale yellow. It is the eggs that give it that color.

A True Key Lime Pie

1 homemade or store bought graham cracker crust

3 large egg yolks

1 can sweetened condensed milk

1/2 cup fresh key lime juice

Whisk the egg yolks for a few minutes or until light in color. Beat in the sweetened condensed milk. When fully combined beat in the lime juice. It will begin to thicken immediately. Continue stirring until fully combined. Pour into the pie shell.

Because of the concern of raw egg products, the pie can be baked. Bake at 325 degrees for 15 minutes. Baking will firm it more. Let cool and serve.

Be native and forgo the meringue or whipped cream. It doesn't do the pie justice.