ROASTED SWEET POTATO SPEARS WITH BACON VINAIGRETTE

Steps:

• Put oven rack in upper third of oven and preheat oven to 450°F.
• Peel sweet potatoes, then cut each lengthwise into 6 spears.
• Cut spears in half crosswise if desired, then arrange in 1 layer in a large (17- by 12-inch) shallow baking pan.
• Cook bacon in a 10-inch heavy skillet over moderate heat, stirring, until browned and crisp, 10 to 15 minutes.
• Transfer with a slotted spoon to paper towels to drain, then pour bacon fat through a fine-mesh sieve onto potato spears and toss with 2 spatulas to coat.
• Sprinkle spears with 1/2 teaspoon salt and 1/4 teaspoon pepper and roast (uncovered), 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, then add oil and heat over moderate heat until hot but not smoking.
• Stir in white part of scallions and remove from heat.
• Stir in vinegar, water, remaining 1/2 teaspoon salt, and remaining 1/4 teaspoon pepper and pour over potato spears.
• Sprinkle potatoes with scallion greens and serve warm.
• Cooks' note: Bacon can be cooked and sweet potatoes can be cut and tossed with bacon fat (but not salt and pepper) 1 day ahead. Cool potatoes, uncovered, then chill, covered with plastic wrap. Chill bacon separately, covered. Sprinkle potatoes with salt and pepper and bring to room temperature before proceeding.