2 red onions, halved
2 tablespoons extra-virgin olive oil
3 medium carrots, cut into large chunks
4 cloves garlic, smashed
1 tablespoon all-purpose flour
1 pound dried black turtle beans, picked over, rinsed and drained
1 smoked turkey drumstick (1 3/4 to 2 pounds)
2 tablespoons pickling spice, tied in cheesecloth
3/4 teaspoon red pepper flakes
Kosher salt and freshly ground pepper
1/2 cup chopped fresh cilantro
Sour cream and/or lime wedges, for garnish (optional)