Dried pears are a tasty, portable and healthy snack. Keep in mind that the more flavorful the fresh pears you start out with are, the more delicious the dehydrated version will be. However, for the best results drying them in your oven, start out with slightly under-ripe pears.
Peel core the pears
Slice off the stem and base ends of the pears. Cut each pear in half and use a paring knife to cut out the cores and seeds. Use a vegetable peeler to peel the pears.
Slice the pears
Cut the pears into slices or small chunks, whichever you prefer. In either case, the pieces should be approximately 1/4-inch thick.
As you slice the pears, drop the pieces into acidulated water to prevent them from browning. You can make acidulated water by adding 1 1/2 tablespoons of vinegar or lemon juice to a quart of water. Leave the slices soaking in the acidulated water while you finish slicing the rest of your pears.
Drain the pears
Once all of the pears are sliced and have had a soak in the acidulated water, drain them in a colander. Let them sit in the colander for 2 to 3 minutes to drain off as much water as possible.
Arrange the pear slices for drying
Place racks inside baking sheets and arrange the pear slices on the racks so that there is space between them on all sides.
Dry the pears
Turn the oven on to its lowest setting, which is usually around 150F. Put the pear-loaded baking sheets in the oven. Let the pears dry until they are leathery to crisp, which can take anywhere from 6 to 10 hours. If your oven is hotter in some spots than others, turn the baking sheets around occasionally so that the pears dry evenly.
Cool the dried fruit
You won't be completely sure if the pear pieces are fully dehydrated until they have cooled (you know how cookies crisp up after you take them out of the oven? Same deal with dried fruit). Remove the trays from the oven. Let the pears cool on the trays for 20 minutes.
After the cooling off period, break one of the pieces of fruit in half. There should be no visible moisture along the surface of the break.
Condition the dried pears
Even after the pears are correctly dehydrated there may still be some residual moisture in the fruit that you can't feel. This shouldn't be enough to prevent the fruit from being safely preserved and mold-free. But you'll have a tastier, better product if you do what is called "conditioning" the dried fruit.
Put the dried, cooled pear pieces into glass jars, only filling the jars about 2/3 full. Cover the jars. Shake the jars a couple of times a day for one week. This redistributes the fruit pieces as well as any moisture they may still contain. If any condensation shows up on the sides of the jars, your fruit isn't dried well enough yet and it needs to go back into the oven on its lowest setting for an hour or two.
Once your dried pears are conditioned, store them in airtight containers away from direct light or heat. It's okay to fully fill the jars at this point: the 2/3 full was just for the conditioning phase when you needed to be able to shake the pieces around.
In addition to enjoying your dried pears as a snack, you can combine them with fresh fruit to make compotes.