In a small bowl, make the flax egg by combining the ground flaxseed and water. Stir and set aside for 5 minutes to thicken.
In a large bowl, add the buckwheat flour, coconut sugar, baking powder, baking soda, and salt. Whisk until well combined. Set aside.
In a medium bowl, add the melted butter, flax egg, milk, and vanilla. Whisk until well combined. Add the sourdough starter discard. Whisk until everything is well combined.
Pour wet ingredients into the big bowl with the dry ingredients. Whisk until combined. The batter should be thick. That’s how we get nice, thick and fluffy pancakes. If it’s looking a little dry or too thick to handle, add a tablespoon more of milk at a time to reach desired consistency. Let the batter sit/rest for 15 minutes.
Heat a non-stick griddle or pan on medium heat. Before scooping the batter, give it a light stir because it will fluff up while resting. Spray or lightly butter the hot pan, then using a 1/4 cup measuring cup, scoop the batter onto the pan. Cook each side for 2-3 minutes. The edges will start to dry and turn golden and that will tell you it’s ready to flip them. Cook the pancakes until golden brown on both sides. Eat right away or keep warm in a 200 degrees F oven until ready to serve. Enjoy with your favorite toppings!