In a large mixing bowl combine flour, granulated sugar, baking powder, and salt.
In a separate bowl, combine milk, oil, melted butter, lemon juice, poppy seeds, and lemon zest. Mix well.
Combine the wet ingredients and dry ingredients; gently mix until just combined.
Beat egg whites until soft peaks form; gently fold into batter.
Let batter rest 5 minutes.
Pour by 1/4 cup onto prepared griddle. Wait until bubbles form on the surface and pop; then flip pancakes until golden brown on both sides.
Make the glaze by combining powdered sugar, lemon juice, and poppy seeds. Whisk until smooth. Pour over pancakes as desired.