ake roast from refrigerator and let stand at room temperature for 2 hours. Preheat oven to 400F, place rack on lowest position. Rub oxtails with tomato paste, place in roasting pan. Add onions, celery, carrots and garlic, toss with just 1 tablespoon of the cooking oil. Roast for 20 minutes.
In the meantime, cut the bone from the rib roast (try to carve as close to the bone as possible). Rub roast with remaining 1 tablespoon oil and generously season with salt and pepper. Heat large frying pan on high heat. When smoking hot, place rib roast, fat side down in pan and sear each side 5 minutes. Remove from pan and let cool for a few minutes. Place the roast right back onto the bones. Use kitchen twine or strips of cheesecloth to tie roast back onto the bones.
When the oxtails and vegetables are done, remove pan from oven.
Reduce the oven temperature to 250F.
Push the oxtail bones and vegetables to the sides, place roast, bone side down in roasting pan. Return pan to oven. Roast for 17-20 minutes PER POUND or until temperature of the middle of the roast is 130F (medium-rare to medium). Transfer roast to cutting board, carefully untie the bones from roast. Cover loosely with tin foil. Rest for 20 minutes.
While roast is resting, make the red wine jus. Keep the oxtails and vegetables in the roasting pan but pour out all but 1 teaspoon of the fat (reserve for Yorkshire Pudding if desired). Place the bones that you've untied from roast in roasting pan 2 burners set on high heat.
Pour in the red wine and cook until wine is reduced by half. Use a wooden spoon to scrape up the bits. Add the beef broth, chicken broth, thyme. Turn heat to medium-low and simmer for 15 minutes. Add any juices accumulated from the rib roast on the cutting board. Turn off heat.
Remove the oxtails and the bones. Strain the jus with mesh strainer, pressing down with wooden spoon to extract out all the juice from the vegetables. Carve the roast, serve with the jus. Give the bones to a nice dog.