Preheat the oven to 350 degrees F. Line a baking pan with parchment paper or a silpat mat.
Make flax egg by combining the ground flax with water. Mix and set aside for 5-10 minutes to thicken.
Place peanut butter, dates, sea salt, and vanilla in a food processor. Pulse until well combined and no big chunks of dates are left. Make sure to scrape the sides every so often. This may take a couple minutes to get it all combined and a consistent texture throughout. Add the flax egg and pulse until combined.
Roll into balls and place on baking sheet. Use a fork and gently press down on each ball to flatten and create a criss cross pattern. Bake for 9-11 minutes. Careful not to overbake! They will firm up as they cool. Once done, sprinkle some coarse sea salt or kosher salt on top. Let it cool on baking sheet for 15 minutes. Then transfer to a wire rack to cool completely.
Enjoy!