1/4 cup all-purpose flour
Kosher salt and freshly ground black pepper
2 lb. boneless, skinless chicken thighs, each cut into 4 even pieces
3 Tbs. olive oil
1 small onion, halved and thinly sliced
2 large cloves garlic, minced
1 14-oz. can diced tomatoes, drained
1 dried bay leaf
1/3 cup good-quality red wine vinegar
1/2 cup lower-salt chicken broth
1/4 cup chopped fresh flat-leaf parsley