To make the dough: In a large bowl, combine the oil, butter, sugars, and zest; beat until combined. (Avoid overmixing at this stage; if the butter is creamed until light and fluffy, the cookies will have a dome shape instead of being flat and crackly on the top.)  

 Add the egg, vanilla, and spices, beating until smooth.

 Add the baking soda, baking powder, salt, and flour; mix until smooth. Cover the bowl and refrigerate the dough for at least 2 hours, until it's stiff enough to scoop easily and hold its shape; overnight is fine.

To assemble and bake: Preheat the oven to 350°F. Lightly grease two baking sheets, or line with parchment.  

 Put the sugar for coating in a bowl and combine with the spices. Rub the zest into the mixture, stirring until well blended.  

Scoop the chilled dough by the tablespoonful (a level tablespoon cookie scoop works well here) and roll in the sugar to coat.  

 Place the balls of dough on the prepared baking sheets, leaving 1 1/2" between them.

 Bake the cookies for 12 to 15 minutes, until the edges just begin to brown. Remove them from the oven and let them cool on the pan for 10 minutes before transferring to a rack to cool completely.  

 Storage information: Store cookies in an airtight container at room temperature for up to two weeks; freeze for longer storage.