Plum Jam for Sweet-Milk Biscuits

Stir together plums, sugar, and salt in a large pot. Bring to a boil over medium-high heat, stirring frequently. Cook, stirring frequently, until thickened to the consistency of very thick honey, about 15 minutes. Stir in lemon juice. Let cool to room temperature. Can be refrigerated in an airtight container up to 1 month.