1Heat oven to 400º. Grease jelly roll pan, 15 1/2 x10 1/2 x1 inch. Spread vegetables, onions and garlic in pan. Bake uncovered 45 to 60 minutes or until vegetables are deep golden brown and tender.
2Remove vegetables from pan; place in 4-quart Dutch oven. Pour 1/2 cup of the cold water in pan. Scrape pan to remove browned particles; add water and particles to vegetables.
3Heat vegetables, remaining cold water and remaining ingredients to boiling; reduce heat to low. Cover and simmer 1 hour, stirring occasionally.
4Cool broth slightly; strain broth. Cover and refrigerate up to 3 days or seal tightly and freeze up to 3 months. Stir before using.