1/2 lb. bacon, cut crosswise into 1/2-inch-wide strips
4 lbs. medium sweet potatoes (about 7)
salt and freshly ground black pepper
1/4 cup extra-virgin olive oil
3 scallions, thinly sliced, white and green parts kept separate
2 tablespoons sherry vinegar
1 tablespoon water
Put a rack in upper third of oven and preheat oven to 450 F.
Cook bacon in a 10-inch heavy skillet over moderate heat, stirring, until browned and crisp, 10 to 15 minutes.
Meanwhile, peel sweet potatoes and cut each lengthwise into 6 spears. Cut spears in half crosswise if desired, and arrange in one layer on a large baking sheet.
Transfer bacon with a slotted spoon to paper towels to drain. Pour bacon fat through a fine-mesh sieve onto potato spears and toss with two spatulas to coat. Sprinkle spears with 1/2 teaspoon salt and 1/4 teaspoon pepper. Roast, turning every 15 to 20 minutes, until potatoes are tender and edges are browned, 45 minutes to 1 hour. Transfer to a serving dish.
Return bacon to cleaned skillet add oil, and heat over moderate heat until hot but not smoking. Stir in white parts of scallions and remove from heat. Stir in vinegar, water, 1/2 teaspoon salt, and 1/4 teaspoon pepper.
Pour bacon mixture over potato spears and sprinkle with scallion greens.
bacon recipe courtesy of: Gourmet Today: More Than 1000 All-New Recipes from the Contemporary Kitchen, edited by Ruth Reichl; Boston/New York: Houghton Mifflin Harcourt, 2009, p. 635