Wash and dry the apples
Remove cores and seeds
Peel the apples if desired
Slice the apples evenly
Toss slices with lemon juice to prevent browning
Arrange slices in a single layer on dehydrator trays or baking sheets
Set a dehydrator to 135°F to 145°F, or use an oven at its lowest setting
Dehydrate until the slices are dry and leathery
Flip slices halfway through if using an oven
Cool completely before storing
Store in an airtight container in a cool, dry place