Preheat oven to 225˚F. Line a baking sheet with parchment paper.  Mix salt and zest together, making sure they are well combined. Pour salt mixture onto baking sheet and bake about 70 minutes or until zest is completely dried out. When salt has cooled, pulse a few times in a food processor for a smoother consistency. Divide among small glass jars if gifting. May be stored for 3-4 months in an airtight container.