Preheat oven to the lowest temperature your oven can go — mine was 170°F (77°C).
Line a baking sheet (or two) with parchment paper.
Slice limes into ⅛-inch pieces. Arrange slices on the parchment lined sheet. They can touch but it's ideal not to overlap them a lot. A little overlap is okay as the slices will shrink in the oven.
Bake in the oven for 3 to 4 hours — the time will vary based on your oven, the temperature and how thin they are sliced. Check every hour and rotate the pan. If any of the slices begin to curl, flip them to encourage them to flatten.
When the lime slices are completely dried, remove them from the oven and let cool completely overnight.
Store in an airtight container in a cool, dry place. If stored properly, dehydrated lime slices will keep for up to two years.
Notes
Lime slices turn brown or black the longer you cook them in the oven. To achieve a lighter, lime green color, monitor the cooking time and check them every 15 minutes beginning during hour two.You can use any kind of lime, like key limes, and other citrus too. Depending on the size of the slices, you may need to adjust the cooking times. Big orange slices will take a smidge longer than smaller lime slices.