Begin by sterilizing your jars. Keep them in hot water until you're ready to fill them.
Prepare your ingredients. Chop the apples and tomatoes and have everything else ready to go.
In a large saucepan, combine all of the ingredients and cook them over low heat, stirring frequently until the mixture is tender and slightly thickened. This should take about 35 to 40 minutes.
Once the filling is hot, remove the sterilized jars from the water and fill them with the hot mixture, leaving 1/2-inch headspace at the top.
Use a plastic knife or spatula to remove any air bubbles, then wipe the rims of the jars with a clean, damp cloth to remove any residue.
Adjust the lids and bands until they are fingertip-tight.
Process the jars in a boiling-water canner for 15 minutes. Adjust for altitude if needed, see notes below.
After processing, let the jars cool and check the seals. Label each jar with the date and contents.
Store your jars in a cool, dry place for up to one year.