1
Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce.
Dice potatoes into 1⁄2-inch pieces; place in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes.
Reserve 1⁄2 cup potato cooking liquid, then drain. Return potatoes to pot and mash with sour cream and 1 TBSP butter (2 TBSP for 4) until smooth and creamy, adding splashes of reserved potato cooking liquid as needed. Season with salt and pepper.