Preheat oven to 400° F. Line a large baking sheet with parchment paper.
In a large bowl, combine flour, sugar, cinnamon and salt. Using a fork or your hands (my preferred method) work the coconut oil into the flour mixture until it is evenly distributed and looks like sand.
Add the vanilla to the water and pour over the mixture. Mix with a fork until the dough starts to come together, then use your hands to form into a ball. Split the dough in half and set one piece aside (if it is a warm day, you may want to place the dough in the refrigerator while rolling the other half out).
Generously dust your counter with oat flour to be sure the dough doesn’t stick. Roll out one half of the dough so that it's 1⁄8” thick. You don’t want them too thin or they will fall apart, too thick and they won’t crisp up.
You can now choose to cut into whatever shape you desire. Use a cookie cutter or cut into squares or rectangles with a pizza cutter. Carefully slide a spatula under the dough and place on the baking sheet. You can gather up the scraps and roll out again to make more cookies, just be careful not to overwork the dough.
Bake for 4 minutes, turn the cookie sheet, and then bake for 4-5 minutes more. Watch carefully as they can burn easily. You want the crackers to be golden brown. Allow to cool for a couple minutes before removing from the cookie sheet. Repeat with remaining dough. Crackers will keep in an air- tight container for up to 10 days.
If you have a food processor or spice grinder, you can make your own oat flour for a lot less money than buying it already ground. Simply place rolled oats in processor and blend until you reach a fine flour consistency.