How to Make It
Sterilize your jars, prepare your bands and lids, and have your canning equipment ready.
In a wide, shallow, nonreactive pot, combine the cantaloupe, cucumber, 3 tablespoons of the sugar, the vanilla bean seeds and pod, lemon juice, salt, and calcium water.
In a small bowl, combine the remaining 3 tablespoons of sugar and the pectin powder and set it aside.
Bring the fruit mixture to a boil over high heat. Boil uncovered for 1 minute, and then add the pectin-sugar mixture to the fruit in the pot while stirring vigorously; the jam should thicken quickly.
After the jam sets up, continue to cook for 1 minute. Don’t be tempted to boil the jam longer because it looks thin; cooking the jam too long may cause the pectin to break down and your jam not to jell. Taste for sweetness and add more sugar as needed. Remove and discard the vanilla bean pod and pour the jam into the hot, sterilized jars. Process the jars in a water bath for 10 minutes according to the manufacturer’s instructions. Let the jars sit in the water 1 minute and remove. Again, overexposure to heat may cause the pectin to break down, so stick closely to the cooking and boiling times.