Heat the oil in a nonstick skillet over medium-high heat. Add the onion and carrot and cook, stirring frequently, until the vegetables begin to brown, 8 to 10 minutes. Place in a slow cooker with water, leek tops, celery, turnip, mushroom and seasonings. Simmer on high 6 to 8 hours, or overnight, until vegetables are very soft. Strain off stock and discard vegetables. Variation: Instead of using leeks, you can use a combination of 2 or more of the following: loosely packed spinach leaves and stems, lettuce leaves, tomato skins, fresh mushroom stems, or diced parsnips along with some additional chopped celery and carrot to equal 3 cups vegetables. Makes about 8 cups. Slow cookers and long, slow simmering makes a good broth. A quick browning of onions and carrots intensifies this stocks hearty flavor. >From the cookbook collection of and typos by: Brenda Adams <adamsfmle@sprintmail.com> Formatting by MC_Buster. MC posted 7/20/97 Recipe by: Sharon Claessens, The No-Tofu Vegetarian Cookbook Posted to MC-Recipe Digest V1 #681 by Badams <adamsfmle@sprintmail.com> on Jul 20, 1997