In the same pot, add the onions and carrots. Season to taste, cook until soft. Add the tomato and tomatoes paste and mix well, cook for a couple of minutes, then add the wine. Put the shanks over the veggies and add about 2 cups of the chicken stock. Reduce heat to low, cover pan and simmer for about 1 1/2 hours or until the meat is really tender. Check often, adding more liquid if necessary.