Wash potatoes, cut in half, and place in saucepan of cold water. Cook, covered, over medium heat for 25 to 30 minutes or until tender.
Drain and dice potatoes when cool.
Add vegetables and egg to potatoes, and toss.
Preheat oven to 450 degrees.
In a medium bowl, combine flour, baking powder, baking soda, salt, and sugar.
In a small bowl, stir together buttermilk and oil. Pour over flour mixture; stir until well mixed.