In a small saucepan, combine the peach jam, water, molasses, and vinegar and bring to a boil over medium-high heat, stirring occasionally to combine.
Once boiling, reduce the heat to medium-low and whisk in the tomato paste, soy sauce, coriander, ground mustard, and salt.
Simmer for 6 to 8 minutes, until thickened; the sauce should be reduced to about 1 cup.
Store in an airtight container in the refrigerator for 3 to 4 days.
