I love sparkling water and one of my favorite flavorings is orange. We have been making these for quite a while and they are very simple.
Cut up old oranges into thin slices. Place on a silpat covered baking sheet. Bake at 200oF for 3-4 hours or so. Check on these closer to the end of the cooking time to see if they are starting to dry out. It helps to flip them every half hour. Flipping the slices also gives you the chance to check how dry they are. Some slices will dry more quickly than others so go ahead and remove them. This is especially important to keep in mind if you’re drying various sizes.
They are dry once they aren’t tacky and before they become browned. If the slices begin to brown but don’t feel dry, that’s a sign your oven is too hot! Remove from the oven and let cool completely to room temperature before storing.
We have also dried the orange slices in the dehydrator, which seems to work as well.
Store in an airtight container. These do not need to be refrigerated.