1. Whisk our with baking soda, ginger, cinnamon and salt in a medium bowl.

2. Beat butter with brown and granulated sugars in a large bowl, using an electric mixer on medium, until fluffy, 2 to 3 min. Beat in egg, lime juice and molasses. Reduce speed to low, then gradually beat in our mixture, until just combined. Refrigerate dough in bowl until firm, about 1 hr. 3. Position rack in centre of oven, then preheat to 350F. Line 2 baking sheets with parchment. Stir coarse sugar with lime zest in a small bowl.

4. Scoop out 1-tbsp portions of dough and roll into balls. Dip 1 side into sugar mixture, then arrange, sugar-side up, 2 in. apart, on prepared sheets.

5. Bake until cookies flatten and crack, 10 to 11 min. Let stand for 5 min on sheet, then transfer to a rack to cool completely. Repeat with remaining dough.