Plum Jam

Directions

1. 1
   In a large, nonreactive saucepan, toss the plums with the sugar and let stand, stirring occasionally, until the sugar is mostly dissolved, about 1 hour.
2. 2
   Squeeze the lemon over the plums, add it to the saucepan and bring to a boil, stirring until the sugar is dissolved.
3. 3
   Cook over moderate heat, stirring, until the liquid runs off the side of a spoon in thick, heavy drops, 20 to 25 minutes.
4. 4
   Skim off any scum that rises to the surface of the jam.
5. 5
   Discard the lemon and spoon the plum jam into three 1/2-pint jars, leaving about 1/4 inch of space at the top.
6. 6
   Close the jars and let the jam cool to room temperature.
7. 7
   Store the jam in the refrigerator for up to 3 months.