”Since these potatoes are "hasslebacked," or sliced accordion-style, before baking, the scallions and bacon fat really penetrate; the sour cream and bacon are the icing on the cake. (The dish has been known to elicit marriage proposals from strangers and tears from bacon lovers.)”
6 bacon slices (6 ounces) 1/2 cup sliced white parts of scallions plus 1/3 cup thinly sliced scallion greens (from 1 bunch) 3/4 teaspoon salt 1/2 teaspoon black pepper 6 medium potatoes (2 1/2 pounds) 1 (8-ounce) container sour cream
Cook bacon in a 12-inch heavy skillet over moderate heat, turning over occasionally, until browned and crisp, 6 to 8 minutes. Transfer bacon to paper towels to drain, then carefully transfer drippings from skillet to a small heatproof bowl and stir in white parts of scallions, salt, and pepper.
Put oven rack in middle position and preheat oven to 450°F. Tear off 6 (1-foot-long) sheets of heavy-duty foil.
Make deep crosswise cuts in potatoes 1/4 inch apart, leaving bottom 1/4 inch intact (do not cut all the way through). Place each potato on a sheet of foil and drizzle each with 1 tablespoon bacon-dripping mixture, separating slices to allow some to drip into cuts. Gather up foil around potatoes, crimping foil to tightly enclose.
Roast potatoes until tender, 45 to 50 minutes. Just before serving, stir together sour cream and scallion greens and crumble bacon over mixture. Carefully open foil packets and transfer packets to a platter. Serve potatoes with sour-cream topping.
Cooks' notes: • Potatoes can be roasted on a grill prepared for indirect-heat cooking over medium-hot charcoal (moderate for gas). • Sour-cream topping, without crumbled bacon, can be made 2 hours ahead and chilled, covered. Just before serving, crumble bacon over topping.
