1. Shred sweet potatoes, and Yukon Gold potatoes, peeled, into large bowl.
2. Stir in egg whites, all-purpose flour, salt and pepper.
3. Heat 1/4 inch peanut oil in large skillet until it is barely smoking. Drop batter by heaping tablespoonfuls into skillet.
4. Cook pancakes over medium-high heat 4 to 6 minutes on each side, or until golden-brown. Drain on paper towels and serve immediately.