Preheat oven to 450°. In a large roasting pan, bake soup bones, uncovered, 30 minutes. Add carrots, celery and onions. Bake 30 minutes; drain fat., Using a slotted spoon, transfer bones and vegetables to a large Dutch oven. Add warm water to roasting pan; stir to loosen browned bits. Transfer pan juices to Dutch oven. Add seasonings and enough cold water just to cover. Slowly bring to a boil, about 30 minutes. Reduce heat; simmer, uncovered, 4-5 hours, skimming foam. If necessary, add water during first 2 hours to keep ingredients covered. , Remove beef bones; cool. If desired, remove meat and discard bones; save meat for another use. Strain broth through a cheesecloth-lined colander, discarding vegetables and seasonings. If using immediately, skim fat. Or refrigerate 8 hours or overnight; remove fat from surface., Broth can be covered and refrigerated up to 3 days or frozen 4-6 months.