- 1 1/2 tablespoons vegetable oil
- 1 large red onion, chopped
- 2 white potatoes (about 10 ounces), peeled, sliced 1/2 inch thick
- 2 medium parsnips, peeled, sliced 1/4 inch thick
- 1 carrot, peeled, thinly sliced
- 1 small turnip, peeled, halved, thinly sliced
- 5 cups (or more) water
- 2 tablespoons chopped fresh chives
- 4 teaspoons truffle oil
- Heat vegetable oil in heavy large pot over medium-high heat. Add onion; sauté until tender, stirring occasionally, about 6 minutes. Add remaining vegetables; sauté until deep golden brown, about 7 minutes. Add 5 cups water; bring to boil. Reduce heat to medium, cover and simmer until vegetables are very tender, about 35 minutes. Cool slightly.
- Working in batches, puree soup in blender. Return soup to pot. Thin with more water if desired. Season soup to taste with salt and pepper. Ladle into 4 soup bowls. Sprinkle each with 1/2 tablespoon chives and drizzle each with 1 teaspoon truffle oil. Serve immediately.