In a medium bowl mix together the flour, sugar, baking powder, baking soda, and salt.
In another bowl whisk together the egg, buttermilk, sour cream, and melted butter.
Mix the wet ingredients into the dry ingredients until combined and just moist; batter will be lumpy with some dry streaks. Let rest for 30 minutes before using.
In a large skillet over medium-high heat, using a light coating of oil or cooking spray cook pancakes ¼ cup batter at a time until golden brown on one side, bubbles form on top, and edges start to firm up. Flip and continue cooking until browned.