Heat the oil in a 10-12" non-reactive skillet over medium-high heat. Dredge the chicken pieces in the flour, shaking off any excess. Brown in the olive oil (don't use any more oil than needed to coat the pan). Remove the chicken to a warm plate and set aside.
Sauté the onion and garlic in the pan, adding a little more oil if needed. Add the remianing ingredients and bring to a boil, scraping up any browned bits in the pan. When the sauce comes to a boil, return the chicken to the pan, and nestle it into the sauce, spooning some over the top of the chicken. Lower the heat to medium and cook for 2 minutes on each side. Serve over pasta or rice.