Roasted Frozen Sweet Potatoes With Whipped Crème Fraîche and Granola

I grew up in Hong Kong, so when winter arrives, I find myself nostalgic for the sweet potato vendors who used to suddenly turn up on every street corner when it got cold. I remember walking through the streets, smelling wafts of wok-roasted sweet potatoes, chestnuts, and quail eggs from blocks away. On one end of these carts there'd be a massive wok set over coals, filled with hot pebbles and sweet potatoes, which the vendors would constantly flip to ensure an even roast. They'd hand over a paper bag with whole, piping hot, roasted sweet potatoes inside, the pillowy and bright flesh protected only by a brittle skin. It’s the perfect snack.

One secret to recreating the concentrated and sweet flavor of those whole roasted sweet potatoes is to use the Northern Chinese practice of freezing them before roasting. As the sweet potato freezes, ice crystals form within the cell, slowly rupturing cell walls, transforming the texture of the flesh. As the sweet potato roasts, the water that leeches out of the cells turns to steam, eventually bursting through the skin so that the sugary juices leak out of the sweet potato as a gooey caramel. At that point, the properly roasted sweet potato is done.

Freeze Your Sweet Potato

As Tim Chin has written, based on his own tests (in which he found, for the record, that this method produces the very best whole roasted sweet potato), there's probably even more going on with the freeze-roasting process than just a textural transformation. Cooking the sweet potato from frozen also likely allows it to spend more time in a critical temperature zone from 135° to 170°F (57° to 77°C), when an enzyme in the sweet potato called amylase becomes very active, converting the tuber's complex starches into the (very sweet) simple sugar maltose. This is a phenomenon Kenji López-Alt also takes advantage of in his diced roasted sweet potato and mashed sweet potato recipes.

The resulting sweet potato is so good you can eat it out-of-hand, exactly how it's enjoyed as a street snack in Hong Kong. But it can also be dressed up.

Pumpkin Pie, Deconstructed

Here, I serve the roasted sweet potato with a light but thick whipped cream that's slightly tart due to the inclusion of crème fraîche. For a finishing touch, I sprinkle granola on top. This dessert is really an homage to a sweet potato pie, with the granola acting as a stand-in for the pie crust. Both the whipped cream and the granola provide contrast for the sweet potato: the tanginess provided by the crème fraîche gently complements the potato's sweetness, and the granola adds pops of crunch to offset the silky softness of the flesh.