Preheat your waffle iron.
Prepare the vegan buttermilk by combining the oat milk and apple cider vinegar in a small mixing bowl, whisk, and set aside.
In a large mixing bowl add the flours, baking powder, salt, and sugar to a medium bowl and mix well.
Melt the butter in the microwave, then slowly add to the oat milk mixture, whisking while you pour it in. Add the flax egg and the vanilla extract, and mix well.
Add the wet mixture to the dry mixture and mix well, until few lumps remain.
Cook the waffles according to your waffle maker’s instructions.
Plate the waffles and top them with the fresh strawberry compote, sliced berries, powdered sugar, and warm maple syrup.