Combine onion, garlic, turkey, cumin, oregano, cayenne, pepper, green chiles, chicken broth, and drained beans in a pot or slow cooker.
Simmer on the stove for 2 hours, or cook in the slow cooker on Low for 4 hours.
Just before serving, stir in sour cream.
Do not boil after adding sour cream.
Serve with Jack cheese, Fritos, and jalapeƱos on the side.
Keep warm in the slow cooker or on Low on the stove.
Notes
Do not bring the chili to a full boil after adding sour cream or it can separate. The chili thickens as it sits; add a splash of chicken broth when reheating. Freeze before adding sour cream for the best texture, then stir in fresh sour cream after reheating. Refrigerate leftovers up to 4 days.