Distribute clean tomato skins on dehydrator trays. Use multiple trays instead of over-crowding.
Set the dehydrator to 135 degrees F.
Allow them to dehydrate for 4 hours and then check on progress. If your trays are moveable, rotate them so that the trays on the bottom are now on top.
Dry another 4-6 hours, or until the skins are dry and leathery without any moisture when you touch them.
Place tomato skins in a food processor, blender, or clean coffee grinder and process until it has reached your desired texture.
Once cooled, store tomato powder in a container with an air-tight lid and store in a cool dry place for 12-24 months.
Notes
Oven Drying Instructions: Place tomato skins on baking drying racks set inside baking sheets. Place in the oven at the lowest temperature possible (usually 140-170 degrees F) and prop open the door with the handle of a wooden spoon. This allows condensation to escape instead of just settle back onto the skins. Bake for 5-8 hours.