Lower heat, add onions to skillet and cook, covered, stirring occasionally, until soft and lightly brown, about 10 minutes.
08Remove lid and continuing cooking until deep golden, about 10 minutes more.
09Add garlic and 1 cup water to skillet and bring to a boil, stirring 1 minute.
10Return chicken to skillet, turning pieces to coat, then arrange them skin side up and gently simmer, covered, until cooked through, about 30 minutes.
11Transfer chicken to serving dish.
12Add balsamic vinegar to sauce and boil, uncovered, mashing garlic, until slightly thickened.
13Season with salt and pepper and pour over chicken, then sprinkle with bacon.