Place the first 7 ingredients in a food processor. Pulse 20 times or until potato is very finely chopped.
Heat 1/2 teaspoon oil in a large nonstick skillet over medium-high heat. Spoon about 1 heaping tablespoon batter per pancake into skillet; cook 1 1/2 minutes on each side or until browned. Repeat procedure with remaining oil and batter. Serve pancakes with sour cream; garnish with green onions, if desired.