Step 1
Inspect 8 half-pint jars for cracks and rings for rust; discard any defective ones. Immerse in simmering water until strawberry jam is ready. Wash new unused lids and rings in warm soapy water.
Step 2
Wash hull and crush strawberries in a bowl. Measure berries; you should have about 5 cups.
Step 3
Scrub oranges well under hot running water and pat dry with paper towels. Zest oranges; place zest in a bowl and set aside. Peel oranges and remove all white pith. Divide oranges into segments and remove any white fibrous membranes and seeds. Chop oranges finely and mix into the bowl with the zest.
Step 4
Place crushed strawberries and orange-zest mixture in a large pot over medium heat. Stir in pectin and slowly bring mixture to a full rolling boil. Add sugar and stir to dissolve. Return to a full rolling boil on high heat and boil for exactly 1 minute stirring constantly. Skim off any foam with a ladle or a large spoon.
Step 5
Pack strawberry jam into the prepared jars filling to within 1/4 inch of the top. Run a clean knife or thin spatula around the insides of the jars to remove any air bubbles. Wipe rims with a moist paper towel to remove any spills. Top with lids and tightly screw on rings.
Step 6
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring to a rolling boil cover and process for 10 minutes.
Step 7
Remove the jars from the stockpot and place onto a cloth-covered or wood surface several inches apart. Let rest for 24 hours without moving the jars. Gently press the center of each lid with a finger to ensure the lid does not move up or down. Remove the rings for storage and store in a cool dark area.