Apple, Parsnip & Potato Puree

Combine apples, parsnips, potatoes and garlic in a large saucepan. Pour in cold water to cover, add salt and bring to a boil. Partially cover the pan and simmer over medium-low heat until the vegetables are very tender, 10 to 15 minutes. Drain the potatoes and mash with a potato masher until smooth. Stir in sour cream. Season with salt and pepper.