Basic Vegetable Stock

Name: Basic Vegetable Stock
Ingredients: 2 tablespoons vegetable oil; 3 small turnips, coarsely chopped; 2 stalks celery, coarsely chopped; 1 large onion, coarsely chopped; 1 leek (white part only), halved lengthwise and coarsely chopped; 1 large carrot, coarsely chopped; 8 cups water