Using a sharp knife, cut the carcass into smaller pieces. In a large pot, add the carcass, vegetables, bay leaves, thyme, and spices. Season with salt. Cover with water. Place the pot over medium heat and bring to a boil. Reduce the heat to simmer and cook for 2 hours. Skim off any scum that rises to the surface. Remove from the heat and strain. Let cool and skim off any fat that comes to the surface.