Preheat the oven to 350F and line a baking sheet with parchment paper or silicone baking mat.
In the bowl of a food processor fitted with an "S" blade, process the dates and walnuts together until a crumbly texture is formed. Add in the salt, baking soda, vanilla, ground flax, water, and vinegar, and process again until the batter is relatively smooth. Add in the chocolate chips and briefly pulse, just to combine.
Spoon the batter onto a lined baking sheet, and use your hands to gently flatten the cookie dough. (Tip: Wet your hands with water to prevent sticking!) Bake at 350ºF for 12 minutes, or until the edges are slightly golden. Allow to cool on the pan for 10 minutes, then transfer the cookies to a wire rack to cool completely.
Serve immediately, and store the leftovers in a sealed container in the fridge or freezer for best shelf life. These cookies should last a week in the fridge, and a month or more in the freezer.