Rhubarb-and-Currant Mostarda

Stir together 1 1/4 cups rhubarb, currants, sugar, vinegar, shallot, ginger, mustard seeds, dry mustard, thyme, and salt in a medium saucepan. Let stand at room temperature 20 minutes.

Bring rhubarb mixture to a boil over medium. Reduce heat to low, and simmer, stirring often, until rhubarb is soft, about 10 minutes. Stir in remaining 3/4 cup rhubarb; cook, stirring often, 10 minutes. Remove from heat, and transfer mixture to a resealable container. Let cool 30 minutes before serving.