Prepare your canning jars, water bath canner with simmering water, screw bands and flat lids per manufacturer instructions.

Place oranges in large bowl; remove peels (and stems). Separate each mandarin orange into segments. Remove any white "pith" or "stringy pieces" you find on the segments (they have a bitter taste, and you do not want that). Set aside.

Make syrup: In a small saucepan, heat water and sugar until sugar has melted. Keep syrup warm while you fill canning jars with mandarin orange segments.

Pack orange slices tightly in sterilized, hot canning jars, leaving ½" headspace. Pour warm syrup mixture over mandarin oranges, again leaving ½" headspace. Use a plastic knife or utensil to remove air bubbles from jars by inserting it several times around inside edges. Check headspace to make sure it is still ½". Add or remove syrup as necessary to maintain correct headspace. Use a damp cloth to wipe rims of each jar to remove any residue that would prevent jars from sealing.

Place flat lids on each jar, then add screw bands (or rings), and screw them on, tightening to fingertip tightness. Put jars on canning rack, then lower rack into the pot of simmering water. Make sure water level is 1" above the top of the jars. Add additional water, if necessary. Turn heat up to Medium High. Cover canner.

Bring water to a gentle rolling boil, then set timer; process for 10 minutes once boiling. If you live above 1,000 feet elevation, process the jars for 15 minutes. When done, turn off the heat; remove lid. Let jars sit in the hot water for 2-3 minutes then remove them, one at a time, using canning tongs.

Transfer HOT jars onto a dish towel on the countertop. NOTE: Do not put hot jars directly on countertop because temperature variances could cause jars to crack. Let jars cool completely (overnight is best). As they begin to cool, you should hear a "ping" or "popping" sound as each of the lids seal.

After jars have cooled completely, make sure they have all successfully sealed. Use a fingertip to press down in the middle of the jar lid. If it pops back or is raised in the middle, that jar didn't seal properly. Refrigerate and use it fairly soon. Carefully remove screw bands off the sealed jars for long-term storage. Wipe jars to remove any sticky residue. Label jars; store in a dark closet or pantry. Enjoy!