Classic Strawberry Jam

Directions

1. 1
   In a large saucepan, bring strawberries up to a simmer over medium-low heat, mashing roughly with a potato masher or flat spoon.
2. 2
   Add sugar and lemon juice, stir, and bring up to a simmer for 2 minutes.
3. 3
   Add butter and bring to a vigorous boil, stirring often, and cook for 10 to 20 minutes, periodically measuring the viscosity of the jam by dabbing a spoonful onto a plate and tipping the plate.
4. 4
   Once the jam slows its drip down the plate (it should no longer run like a syrup), remove from heat and skim off foam.
5. 5
   Fill jars that have been washed, rinsed, dried and boiled in a pot of water for 3 minutes to 1/4 inch from the top.
6. 6
   Fasten lids securely and boil jars in a vat of water (be sure jars are completely submerged) for 15 minutes.
7. 7
   Remove jars with tongs and let cool upright.
8. 8
   Check for secure seals on jars (lid should not spring when touched) and store in a cool place away from light for up to a year.
9. 9
   Any jars that do not achieve a proper seal should be refrigerated.