Melt butter and 1 tablespoon oil in a nonstick skillet over medium heat. Add onion; saute 15 minutes or until golden. Add brown sugar, and cook 5 minutes, stirring often.
Combine onion mixture, potatoes, salt, and pepper.
Heat 1 tablespoon vegetable oil in a nonstick skillet over medium-high heat. Drop potato mixture into 3 1/2-inch rounds; cook, in batches, 5 minutes on each side or until golden, adding remaining oil as necessary. Press down with a spatula to flatten; top with bacon and pecans.
Cheesy Sweet Potato Hash Browns: Omit onion, brown sugar, bacon, and pecans. Top hash browns evenly with 4 ounces thinly sliced Jarlsberg or Monterey Jack cheese during the last 5 minutes.
Rosemary-Garlic Hash Browns: Omit onion, brown sugar, bacon, and pecans. Add 1 tablespoon chopped fresh rosemary and 1 teaspoon chopped fresh garlic to potato mixture. Cook as directed.