Place the mustard-vinegar mixture along with the oil, herbs and seasonings in a blender and mix for about 10 seconds or until fully combined.
Transfer to a glass bowl and let stand for 30 minutes to let the flavors meld. Give the dressing a good whisk immediately before serving.Makes 1 cup of dressing.
NOTE: Any oil labeled "vegetable oil" or "salad oil" is fine for this basic recipe. You can also use any light, neutral-flavored oil like safflower, canola or soybean oil.