Preheat oven to 375°. Cook potatoes in boiling salted water to cover 8 to 10 minutes or until tender. Drain.
Combine eggs and next 6 ingredients in a medium bowl; whisk until well-blended. Stir in potato.
Spoon about 1 tablespoon egg mixture into each cup of a lightly greased mini muffin pan. Bake 13 to 15 minutes or until lightly browned. Cool in pans on wire racks 5 minutes. Remove from pans; top each quiche with about 1/2 teaspoon sour cream, and garnish, if desired. Serve quiches warm or at room temperature.