Cover pan, bring pan to a boil, then reduce heat to medium.
Simmer covered for 10 minutes.
Uncover, then simmer for around another 15 minutes, or until mixture has thickened a bit (not too much - remember, it will thicken more once cooled.) Stir periodically.
Ladle hot salsa into hot jars.
Leave 2 cm (½ inch) headspace.
Debubble, adjust headspace.
Wipe jar rims.
Put lids on.
Process in a water bath or steam canner.
Process jars for 20 minutes; increase time as needed for your altitude.