In the same pot, add the onion, carrot, celery, red pepper flakes, and hot sauce.
Season with salt at this point to help draw out the moisture from the vegetables. Saute until soft and
translucent, about 8 minutes.
Add the tomato paste and mix well. Return browned shanks to the pan and add the white wine and reduce liquid by half, about 5 minutes.
Add the bouquet garni and 2 cups of the chicken stock and bring to a boil.
Reduce heat to low, cover pan and simmer for about 1 1/2 hours or until the meat is falling off the bone. Check every 15 minutes, turning shanks and adding more chicken stock as necessary.
The level of cooking liquid should always be about 3/4 the way up the shank.