Not into cranberry sauce? This is Italian mostarda, a fruit-based condiment with a spicy, savory edge. We used grapes here, but pears or apples would be delicious, too.
In a medium saucepan, heat the mustard seeds and oil over low, stirring often, just until the seeds begin to pop, about 1 minute. Add the grapes, onion, cherries, sugar, vinegar, thyme, bay leaves, crushed red pepper, and 2 tbsp. water. Bring to a simmer over medium-high heat. Adjust heat as needed to maintain a steady simmer and cook, stirring occasionally, until the fruit is tender and the liquid is syrupy, 40 to 45 minutes.
Stir in the mustard powder and Dijon. Remove from heat; let cool to room temperature. Discard the thyme sprigs and bay leaves. Serve the mostarda warm or at room temperature.