Pre-heat oven to 300 degrees and line baking sheets with parchment paper.
In a medium bowl combine rye flour, kosher salt, and sesame seeds. Add the starter, coconut oil, and maple syrup and mix until a firm dough comes together.
On a floured surface, knead dough until all ingredients are incorporated. The dough should be a little tacky and most importantly roll easily. Add a little bit of extra flour or water to dough if needed.
Divide dough into 4 small equal balls. Roll balls out on a floured surface into a large rectangle (or as close as you can get) 1/8 in thin (or thinner). Lift the dough often and add a little flour to the surface so the dough doesn't stick.
With a dough cutter, cut out 1-2" squares and prick with a fork. Gently place squares on parchment paper very close to one another. Sprinkle with sea salt.
Bake for 20-30 minutes, dependent upon how thick they are. Check after 20 minutes to make sure they're not burning.
Cool completely and then store in an airtight container.