For me, there is no better preserve than homemade blackberry jam. And it somehow tastes even better if you go out and pick the blackberries yourself!
Preheat oven to 250 degrees.
Wash the berries. Place berries and sugar in a dutch oven or stock pot.
Zest the lemon and blanch the zest in hot water for 2-3 minutes to remove the bitter oils from the skins. Add blanched zest, along with the juice of the lemon, to the dutch oven. Stir everything together.
Set the dutch oven on the stove top over high heat. Stir berries regularly to avoid burning. You want the mixture to cook and bubble away vigorously. Taste periodically for sweetness and add a little more sugar, if you think it needs it. Trust yourself. I personally like my blackberry jam nice and sweet.
While your jam cooks, get your jars ready. A while back, Paul took a preserving class with local jam goddess, June Taylor, who taught Paul a very easy sterilizing technique: place clean jars on a baking sheet in a 250 degree oven while your jam is cooking (for at least 10 minutes). Paul also puts a glass Pyrex pouring cup in the oven along with the jars to sterilize the all the glass. He then washes the lids and seals in hot soapy water. (If you use Weck's glass lids, you can sterilize them in the oven too.)
Set everything aside when sterile and wait for jam finish cooking.
Your jam should be done as it becomes thick and syrupy after about 10-15 minutes of bubbling. There is a whole jamming mystery about achieving the proper set and there is also a lot of subjectivity about this notion. I followed Paul's suggestions and he said to look for the the foam to lessen and the bubbles settle down a bit as the jam reaches the point of doneness.
Scoop hot jam into the jars using the sterile Pyrex pourer. Be sure to use a clean paper towel to wipe any excess jam for the lip of the jar before you pop the lids on. Seal immediately and the hot jam locks everything into place.
makes 6 cups
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