Combine ingredients: To a medium bowl or jar, add leftover sun dried tomato oil, vinegar of choice, dijon mustard, and a pinch of salt and pepper.
Shake well to mix: Whisk or shake well until mustard is well combined and the vinaigrette starts to thicken. Test a small amount and add more salt or pepper if needed, to taste.
For a thicker vinaigrette: Combine vinaigrette ingredients in a blender or food processor and add a few small slices of sun dried tomatoes. Pulse to chop the tomatoes for a vinaigrette with small pieces of sun dried tomatoes inside, or puree the ingredients for a thicker dressing where the tomatoes are completely blended.
