In a large stock pot bring all ingredients up to temperature over medium low heat.
Meanwhile prepare jars by washing jars in warm soapy water and bringing to a boil in water bath canner or large stock pot to sanitize. Leave in hot water with lids until ready to use.
Mash strawberries with a potato masher until desired consistency is reached. Stir and increase heat to medium high.
Stir frequently to prevent scorching. Boil mixture until it reaches 220 degrees or gel stage as determined by using the back of a frozen spoon to test.
Ladel jam into hot jars leaving ¼ inch of headspace. Wipe down rims and center lid. Hand tighten ring and return to boiling water for 5 minutes processing time.
Remove from water and set on a towel to cool. Check seal before storing.