Blueberry Lemon Jam

Directions

1. 1
   Have ready four 8-ounce canning jars with 2-piece lids.
2. 2
   Fill a large pot with water and bring to a boil over high heat, then decrease the heat so that the water is barely bubbling.
3. 3
   Immerse the pint jars in the canning kettle.
4. 4
   Place the rings and lids in a separate small saucepan and cover them with hot water.
5. 5
   Leave the jars and lids immersed while you cook the jam.
6. 6
   If you dont have a candy thermometer to tell you when the jam is done, place a small plate in the freezer.
7. 7
   Combine the lemon slices, water, and 1/2 cup of the sugar in a large saucepan over medium-high heat; bring to a boil and cook undisturbed until the lemon slices are translucent, about 20 minutes.
8. 8
   Add the remaining 3/4 cup sugar and the blueberries; cook, stirring occasionally, until the mixture thickens and reaches 220F on a candy thermometer, 20 to 30 minutes.
9. 9
   If you dont have a candy thermometer, remove the plate from the freezer and immediately spoon a teaspoon of jam onto it.
10. 10
    Let it sit for a few minutes until the jam cools, then tilt the plate and see how much it runs.
11. 11
    It will probably not wrinkle and get firm the way jams with more pectin would, but it should be thick and only slightly run.
12. 12
    If its too runny, continue cooking it down, stirring frequently, until it thickens further.
13. 13
    While the jam is still hot, ladle it into the hot, sterilized canning jars, leaving about 1/4 inch of head space at the top.
14. 14
    Remove any air bubbles by running a long, nonmetallic utensil, such as a chopstick or wooden skewer, between the jar and the jam.
15. 15
    Top with the prepared lids, close tightly, and process for 5 minutes in a hot-water bath with the jars submerged by at least 1 to 2 inches of water.
16. 16
    Remove from the water and let cool, undisturbed, to room temperature.
17. 17
    Besides making that telltale ping when it seals, the lid of a properly sealed jar should be slightly concave and not move; if the lid springs down and back when you press your finger in the center, the lid is unsealed.
18. 18
    If it doesnt seal, process it again or store it in the refrigerator instead of at room temperature.
19. 19
    Store sealed jars in a cool, dry place.