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; add all at once to flour mixture.
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 c. onto prepared skillet.
Wait until bubbles form on the surface and pop; then flip pancakes until golden brown on both sides.
For glaze, combine powdered sugar, lemon juice, and poppy seeds and mix until smooth.
Pour over pancakes as desired.