Heat the oven to 425 degrees F.
Slice the fingerling potatoes into ½ inch coins. Place the sliced potatoes onto a baking sheet and toss with the oil, garlic powder, paprika, salt and pepper. Make sure all the potatoes are evenly coated.
Place the baking dish into the oven and roast for 15 minutes. Remove the baking sheet and give the potatoes a quick toss to make sure they are cooking evenly. Place the baking sheet back into the oven and continue to roast for about 15 minutes more until the potatoes are golden brown. They should be fork tender all the way through. If they are not, roast them for 5-7 minutes longer.
Remove the roasted potatoes from the oven and transfer them into a large bowl. Add 1/3 cup of the mustard herb vinaigrette and toss to combine. Adjust salt and pepper as needed and serve warm.