Combine all ingredients in a heavy saucepan and bring to a boil over medium-high heat, stirring often.
Reduce the heat to medium and simmer, stirring every 15 minutes or so, until the mixture has the consistency of thick jam, about 90 minutes. Taste and adjust the seasoning.
Remove from the heat and pour into sterile jars. Process in a hot water bath and then store in a cool dark place.
If you choose not to process the jars in a water batch, the jam will keep nicely in the refrigerator for up to a month. Or it can be frozen for up to 6 months.