In a small bowl, add ground flax seed and water. Stir combine then set aside to thicken.
In a large bowl, add oat flour, baking powder, cinnamon and salt. Whisk to combine and set aside.
In a measuring cup, combine the milk and apple cider vinegar. Add the maple syrup and vanilla extract.
In a separate deep bowl or cup, add the tahini and a small amount of the milk mixture. Whisk until the tahini is smooth, adding more of the milk as needed. To the bowl with the flour, add the flax mixture, the tahini, and remaining milk mixture. Stir until evenly combined, assuring there aren't any clumps of flour, then set aside while you warm the waffle maker. The batter should rest for about 5 minutes before using. This helps it thicken a bit, however, you don't want it to sit too long or the waffles will turn out more dense.
Distribute about 1/4 cup for each waffle (this will vary depending on your waffle maker) and cook until golden and crispy. I like to cook mine for a bit longer for crispy edges.
Serve warm with pure maple syrup and enjoy!