Rinse the 15-bean mix well and soak overnight, or use the 1-hour quick soak method (boil 5 minutes, rest 1 hour). Drain and set aside.
Add oil to a Dutch oven and sear turkey tails 3–4 minutes per side. Remove and set aside.
In the same pot, cook onion, bell pepper, celery, and garlic for 4–5 minutes until soft.
Add turkey tails, beans, broth, bay leaves, and all seasonings. Bring to a boil, reduce to low heat.
Simmer 2 to 2½ hours, stirring occasionally, until beans are tender and turkey is shredding. Remove, shred, and return meat to soup.
Add greens and vinegar. Simmer 25–30 minutes until tender.
Add smoked sausage during the final 20–30 minutes for richer flavor.
Add salt, pepper, or hot sauce as needed.
Spoon into bowls with a scoop of white rice, garnish, and enjoy.
