Preheat the oven to 350 degrees Fahrenheit.
In a large mixing bowl, cream together the peanut butter and brown sugar for 1 minute. Add in the vanilla extract and beat for another 30 seconds.
In a separate mixing bowl, whisk together the dry ingredients (oat flour, baking soda, and salt).
While beating the peanut butter mixture, slowly add in the oat flour mixture and beat until a crumby dough forms. Add the water and continue to beat until distributed. Do not over mix.
Line two baking sheets with parchment paper.
Roll the dough into balls (about 1 1/2 - 2 tablespoons per cookie), drop onto parchment-lined pan, and flatten with a fork one way and then the other to create a crisscross pattern.
Bake for 8-12 minutes, or until just starting to turn golden at the edges (they bake FAST, so watch them carefully).
Cool completely on the pan before moving or enjoy.
Store in an airtight plastic container to keep the cookies soft and chewy.