Preheat oven to 425°F.
Place the petite red potatoes in a large mixing bowl.
Add the olive oil, dijon mustard, fresh grated horseradish, fresh rosemary, garlic powder, sea salt, and ground pepper.
Toss to thoroughly coat the potatoes in the mixture.
Place the potatoes in a single layer on a large baking sheet.
Bake for 45 minutes, or until the potatoes are golden brown, stirring once every 15 minutes. Serve immediately and garnish with more fresh grated horseradish.