Use a knife to horizontally score the plantains then remove the peel.
Slice the plantain into 1'' discs, they don't have to be extremely thin in size
Lay the plantain pieces on the dehydrator trays
Set the temperature to 70c (158f) and timer for 12 hours
Once the plantains have dried out place them in a spice grinder, if using a small grinder you might have to do it in batches or use a dry container (ninja or vitamix) or food processor and ground into a fine consistency.
Be sure to store the flour away from sunlight (in a cool place).
Make sure to label the flour (it should last for several months).
You can use a mandolin slicer or paring knife to slice the plantain, you want them to be more on the thin side.
The flour should be smooth, almost like powder.
Use a spice grinder (for best results to mill the flour