Heat the oil in a large Dutch oven over medium high heat. Add the onion and garlic to the pan; saute for about 5 minutes. Add the buffalo; cook for about 5-7 minutes or until browned, stirring to a crumble. Stir in the chili powder and cayenne pepper.
Add the wine to the pan and boil until reduced by half, about 3 minutes. Add the beef stock, potato, tomato paste, salt, oregano, basil, bay leaf Worcestershire sauce and sage. Bring to a boil. Reduce heat and simmer for about 1 hour or until the potato is very tender. Adjust seasonings to taste with salt and freshly ground black pepper. Serve with grated cheddar cheese, sour cream, chopped scallions (optional).