1.
Thoroughly wash the turmeric and ginger roots in lukewarm water until completely clean. Pat dry with a dish towel to remove moisture.
2.
Cut the roots into slices about 3 millimetres thick. Use a knife, food processor, or vegetable slicer.
3.
Preheat the oven to 100 degrees and line a baking sheet with parchment paper.
4.
Lay the slices flat on the parchment paper separately, without overlapping.
5.
Dry in the oven for about 3 hours. Wedge a thin cooking spoon in the oven door to allow moisture to escape.
6.
Remove the tray from the oven. If there are soft or moist spots, bake for another 15–30 minutes until completely dry.
7.
Let the tray cool for about 5 minutes. Pieces should break like chips; if not, dry longer.
8.
Let the root pieces cool for another 15 minutes.
9.
Place the dried ginger and turmeric pieces separately into a high-powered blender, food processor, or coffee grinder and grind into powder.
10.
Store the powder in airtight containers and protect from moisture. Shelf life up to one year.