Place oxtails in cold water and bring to a boil. Lower heat and simmer 30 minutes. Drain and cool. In a heavy-bottomed Dutch oven, heat oil until smoking. Place onion, carrots and celery in pot and cook until golden brown, about 10 to 12 minutes. Add wine, anchovy, chicken stock, tomato sauce and rosemary and bring to a boil. Add oxtails to liquid, cover and bring to a boil. Lower heat to simmer and cook 1 1/2 hours or until fork tender. Serve with soft polenta.
Saute the onion and garlic in the olive oil over medium heat until translucent, but not brown (about 10 minutes). Add the thyme and carrot and cook 5 minutes more. Add the tomatoes. Bring to a boil, lower the heat to just bubbling, stirring occasionally for 30 minutes. Season with salt to taste. Serve immediately, or set aside for further use. The sauce may be refrigerated for up to one week or frozen for up to 6 months.