In a medium bowl, whisk together the buttermilk, egg, and melted butter.
In another bowl, mix together white flour, buckwheat flour, sugar, salt and baking soda. Pour the dry ingredients into the egg-mixture. Stir until the two mixtures are just incorporated.
Heat a griddle or large frying pan to medium-hot, and place 1 tablespoon of butter, margarine or oil into it. Let the butter melt before spooning the batter into the frying pan, form 4 inch pancakes out of the batter. Once bubbles form on the top of the pancakes, flip them over, and cook them on the other side for about 3 minutes. Continue with this process until all of the batter has been made into pancakes.