For the base, combine almond flour, tapioca or corn starch, coconut oil, maple syrup and salt in a large bowl and mix together evenly with a fork until it forms a nice dense crumb. Turn it out into the prepared pan and press it evenly into the base. Bake for 12-15 minutes. Transfer to a rack and let cool for at least 15 minutes.
For the caramel, combine tahini, maple syrup, brown sugar, coconut oil, lemon juice, vanilla and salt in a medium saucepan and place over medium heat. Stir constantly until it begins to simmer gently and then continue to simmer for 30 seconds. Do not over-boil. Immediately pour it over the cooled crust and then refrigerate for at least 1 hour until firm.
For the topping, melt chocolate with coconut oil in a microwave safe bowl and microwave on high power for 20 second increments, stirring in between until chocolate is completely melted and smooth. Pour it over the caramel layer and spread it out evenly. Sprinkle with sea salt flakes and then let refrigerate until set before cutting into bars. Store bars in the fridge in an airtight container.