Place the chicken carcass and the celery, onion and carrot in a pot and cover with water, Add peppercorns and bay leaves, cover, and bring to a boil. Reduce to simmer and cook for 1 hour to extract the flavor. Strain the solids and set aside to cool.
Return the pot to the stove and bring to a boil; cook until reduced to a nice thick demiglace (you should only have about 2 cups of liquid after reducing).
While the stock is reducing, pick out any pieces of chicken from the carcass and combine them in a pot with the cooked black beans. Dice the cooked carrot from the stock and add it to the black beans, then add 1-2 cups of the demiglace and the cilantro. Cover and simmer for 20 minutes, then puree, if desired. Season to taste with salt and pepper and thin with more demiglace if the soup is too thick for your liking.
Freezes well.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2018/08/black-bean-soup/