Stir in the tomato puree and let the liquid bubble. Reduce the heat for about five minutes. Add thyme sprigs and pour in chicken stock.
Add the chicken legs back to the pan, then cover and simmer on low heat for an hour. Once the chicken is tender, remove from the sauce and keep heated. Boil down the sauce for 10 more minutes until it has a syrup consistency.
Put the chicken legs back in and serve.
