The classic Key lime pie always strikes me as a modern sort of confection, but it is a genuine old-timer, a pie that South Florida’s people were devouring with glee back in the 1890s. Key limes are walnut-sized citrus fruits with an uneven yellow-green rind and a cool, pale green inner pulp. Though they thrive in the necklace of islands that make up the Florida Keys, Key limes are not from there. Most likely, they blew in long ago on trading ships, by way of South Asian ports of call.

The traditional Key lime pie is simple, elemental, and delicious. Sweetened condensed milk has been in the American pantry since the 1860s, and without pastureland nor dairy cows to provide milk, residents of the Keys took to it early on and spun it into a local specialty that the nation adores. The original Key lime pie called for a baked pastry crust, but graham cracker crusts were embraced as an early variation, and they are my favorite.

Look for Key limes in small net bags in the produce section seasonally, or order Key lime juice by mail. Allow a little time for this pie. While it’s one of the simplest to put together, the filling needs three hours to chill once it’s made.