Preheat waffle iron according to manufacturer's instructions.
Make the Flax Eggs: In a small bowl, combine the ground flax and water. Stir, and set aside to thicken.
Make the Vegan Buttermilk: If your milk is cold, warm it for a minute in the microwave, otherwise it will cause the coconut oil to harden in the batter. In a large measuring cup or bowl, measure 3 1/2 cups of plant-based milk. Add the apple cider vinegar (or lemon), stir a little with a spoon and set aside to curdle.
In a large bowl, whisk together the flours, baking powder, salt and sugar.
Add the flax eggs, vegan buttermilk, melted coconut oil and vanilla to the dry ingredients. Stir until just combined with a large wooden spoon, being careful not to over mix. The batter should be fairly thick, if it's too runny add a few tablespoons more of flour. If it's too thick, add a little more water.
Spray waffle iron with oil (unless your waffle iron is non-stick).
Pour the recommended amount of batter onto hot waffle iron (I pour about 1/4 cup in the center), and cook until the waffle is golden brown on both sides.
Serve immediately, or keep in a warm oven (200 degrees F) until ready to serve. Top with fresh berries, coconut whip, vegan butter, maple syrup and anything else you like!