In a medium bowl, combine buckwheat flour, all-purpose flour, baking powder, and sugar.

Create a well in the center of the dry ingredients.

In a small bowl, whisk together buttermilk, egg substitute or egg whites, water, and melted margarine.

Pour the wet ingredients into the well in the dry ingredients.

Stir until just moistened; do not overmix.

Heat a griddle over medium heat and coat with cooking spray.

Spoon 2 tablespoons of batter onto the hot griddle for each pancake.

Spread each dollop of batter into a 4-inch circle.

Cook until bubbles form on the surface and the edges look firm.

Flip the pancakes and cook for another 2-3 minutes, or until golden brown.

Serve immediately.