Orange zest
Make sure that the Oranges have not been sprayed with pesticides.
Peel an orange or two as you normally would for eating, trying to keep the pieces of peel as large as possible. Lay them skin side down on a cutting board, and with a sharp knife at a slight angle to the board, shave away the interior pith until you see the bright orange of the exterior peel. Its important to remove all of the pith as it imparts a bitter flavor.
Once the pith is gone, you can slice the peel into thin, short strips to prepare for drying. Spread the strips in a single layer on a sheet of foil and put them in a 250 F oven until you see them start to curl - about 20-30 minutes. Remove from the oven and let them cool completely. Store in an airtight container in the refrigerator. This method works with lemon peel too.