Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or lightly spray with cooking spray and set aside.
Blend together the date paste, peanut butter, flax meal, baking soda, vanilla extract and vinegar together until well combined. Add in the flour and mix together— it should be fairly sticky when held together but not too tacky.
Roll mixture into ~2 tablespoon balls, then place on prepared baking sheet. Repeat with rest of the dough, then dip a fork into flour and gently press onto the cookies to make a hashtag pattern. Bake for 10 minutes, until just set. The cookies will be chewy!
Remove from oven and let cool, then drizzle on chocolate and top with flaked sea salt, if using.