Roasted Sweet-Potato Spears with Bacon Vinaigrette

Ingredients

• 0.5 pound bacon sliced
• 0.5 teaspoon pepper black
• 0.3 cup olive oil extra-virgin
• 1 teaspoon salt 
• 3  scallions thinly sliced sliced
• 2 tablespoons sherry vinegar 
• 4 pounds sweet potatoes ( 7)
• 1 tablespoon water 

Equipment

• frying pan
• paper towels
• oven
• sieve
• baking pan
• spatula
• slotted spoon

Directions

1. Put oven rack in upper third of oven and preheat oven to 450°F.
2. Peel sweet potatoes, then cut each lengthwise into 6 spears.
3. Cut spears in half crosswise if desired, then arrange in 1 layer in a large (17- by 12-inch) shallow baking pan.
4. Cook bacon in a 10-inch heavy skillet over moderate heat, stirring, until browned and crisp, 10 to 15 minutes.
5. 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.
6. 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.
7. Transfer to a serving dish.
8. 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.
9. Sprinkle potatoes with scallion greens and serve warm.