1/2 cup reduced-fat sour cream
1 teaspoon freshly grated lemon rind
1/2 teaspoon freshly ground black pepper, divided
2 cups leftover mashed potatoes (about 15 ounces)
6 tablespoons all-purpose flour
1/2 teaspoon baking powder
1/8 teaspoon kosher salt
1 egg white, beaten
1/2 small yellow onion, minced
2 tablespoons safflower oil, divided
1/4 pound thinly sliced smoked salmon, torn into bite-sized pieces
1 to 2 tablespoons chopped fresh chives
Preheat oven to 200°. Place a wire rack on a baking sheet.
Combine sour cream, lemon rind, and 1/4 teaspoon pepper in a small bowl. Cover and chill.
Combine potatoes, flour, baking powder, remaining 1/4 teaspoon pepper, salt, egg, egg white, and onion in a medium bowl. Heat a large nonstick skillet over medium heat. Add 1 1/2 teaspoons oil; swirl to coat. Scoop about 1 1/2 tablespoons potato batter per pancake onto hot pan, for a total of 8 pancakes; flatten each slightly. Cook pancakes 2 to 3 minutes on each side or until golden brown. Place pancakes on rack on baking sheet; place in oven to keep warm. Repeat procedure in 3 more batches with remaining oil and remaining potato batter. Top pancakes with sour cream mixture, salmon, and chives.