Preheat the oven to 300 degrees F. Line a large baking sheet with parchment paper and set aside.
If your dates are not soft and juicy, place them in a bowl. Cover them with boiling water. Let them soak and soften for about 5 minutes.
In another small bowl, stir together the ground flaxseed and water. Set mixture aside for 5 minutes to thicken/gel slightly.
Once the dates have softened, drain and transfer them to the bowl of a food processor. Add the flaxseed mixture, peanut butter, lemon juice and vanilla extract. Pulse the food processor a few times before running it on high. Stop to scrape down the sides of the bowl if necessary and continue until you have a relatively smooth paste.
Add the almond flour, coconut flour, salt, and baking soda to the food processor. Run the motor on high until you have a sticky and well mixed dough.
Transfer the cookie dough into a medium bowl. Fold in the chocolate chips with a spatula until they are evenly mixed throughout the dough.
Divide the cookie dough into 10 rough portions (each portion is about a heaped tablespoon full) and place them onto the baking sheet. Now, lightly oil your hands and roll each dough potion into a smooth ball before flattening them into about 2.5" diameter cookies. Arrange the cookies on the baking sheet. These cookies will not spread as they bake, so they won’t need much space.
Bake cookies until deep golden on the undersides and lightly cracked on top, about 15-16 minutes.
Transfer cookies to a cooling rack to cool completely before serving.