Step 1

Preheat the oven to 175°. Set large wire racks on each of 3 large rimmed baking sheets. Arrange the orange slices in a single layer on 2 of the racks. Dry the oranges in the upper and lower thirds of the oven for about 4 hours, until the flesh is slightly tacky and the peel is crisp; flip the orange slices and shift the pans from top to bottom and front to back halfway through drying. Let the slices cool completely on the racks.

Step 2

Meanwhile, trim the ginger as necessary to fit the width of a mandoline. Slice the ginger into lengthwise strips 1/8 inch thick; discard the end pieces. Arrange the ginger in a single layer on the remaining rack. Dry the ginger in the oven for about 3 hours, until dry to the touch; flip the ginger and shift the pans from front to back halfway through drying. Let the ginger cool.

Step 3

Divide the oranges, ginger and spices into 8 bags and secure with twine.