Tarte tatin is a French dessert usually made with apples; the fruit is arranged in a pan of simple caramel and baked with a round of pastry draped over the top. Once the pastry is golden brown and crisp, the tart is inverted onto a plate to reveal shiny, tender, caramel-coated apples.
This version is a savory take, using thinly sliced sweet potatoes (between ¼” and ⅛”—no need to break out a mandoline) and frozen puff pastry. In lieu of making a caramel, you’ll butter and sugar the bottom of the pan, which will liquify and turn caramelly all on its own in the oven. You’ll also brush each layer of sweet potato slices with a spiced harissa mixture, which adds a little heat and earthiness to every bite. A looser and milder harissa, like Mina brand, easily slicks over the potatoes and balances their sweetness well. The final dish makes a quick and easy dinner party side or weeknight vegetarian main—and goes especially nice with a few quick-pickled red onion slices scattered on top.