Radish Goat Cheese Galette

Name: Radish Goat Cheese Galette
Ingredients: For The Crust; 4 ounces unsalted butter; 2 cups unbleached all purpose flour; 6 ounces sour cream (not low fat or fat free); 2-3 tablespoons ice water; 1 pinch kosher salt; Radish and Goat Cheese Galette; 5 ounces chevre goat cheese; 1 tablespoon sour cream (optional); 1 sour cream pie crust, see above; 1 tablespoon dijon mustard; 6 medium size, firm radishes, sliced thin with a mandoline or very sharp knife; 1/2 tablespoon sherry vinegar; kosher salt and black pepper to taste; 1 tablespoon fresh rosemary leaves, or to taste