Preheat oven to 200°. Pulse salt, lemon zest and ginger in a food processor until blended. Transfer to an 8-in. square baking dish. Stir in lemon juice. Bake, stirring occasionally, until dry, 20-25 minutes. Cool completely. Stir with a fork to break up. Store in an airtight container in a cool, dry place for up to 3 months.