Roasted sweet potato, from Tu Casa Mi Casa

Why a steam whistle signals snack time in Mexico City

In Tu Casa Mi Casa, Enrique Olvera reveals the Mexican sweet potato seller’s unusual calling card

A high, steam-driven whistle can mean many things in many different cities, from an express train's arrival, through to the end of the working day on a production line. However, in Mexico City, the Mexican capital, that sound takes on a certain culinary characteristic.

“No matter where you are in Mexico City, as the night starts, you will hear a steam whistle in the distance,” explains Mexico’s leading chef Enrique Olvera in his new book Tu Casa Mi Casa: Mexican Recipes for the Home Cook. “For an untrained ear, it might sound like a shift is ending at a factory, or the whistle of a passing train. For a Mexico City dweller, though, this invariably means that the camote - sweet potato - cart is approaching.

“The vendor keeps an assortment of roasted sweet potatoes in a barrel,” Olvera goes on to explain, “they are kept warm by wood-powered steam that, when released, creates the unmistakable whistle sound.”

That might sound like an unusual, kerbside treat, but as Olvera goes on to say, the camote is made a little bit sugary on the Mexican streets. 

“They are meant to be a sweet treat and you can choose your topping, but the most common one is condensed milk,” he writes.

Fortunately, you don’t need a steam-heated barrel to recreate this treat at home; Enrique includes a detailed step-by-step guide to the making of this dish, as well as a recipe for condensed milk, if you want to have a go at that too.

"Try it out or use the store-bought canned one,” he says. But whatever you do, he insists you "enjoy the sweet potato while it’s hot!” 


Signed copies of Tu Casa Mi Casa are available in our store
Signed copies of Tu Casa Mi Casa are available in our store

For more in-depth local knowledge, as well as plenty of easy-to-follow recipes, order a copy of Tu Casa Mi Casa here.