In a large resealable plastic bag, combine the marinade ingredients.
Discard all the visible fat from the chicken. Put the chicken with the smooth side up between two sheets of plastic wrap. Using a tortilla press, the smooth side of a meat mallet, or a rolling pin, lightly flatten the chicken to a thickness of ¼ inch, being careful not to tear the meat. Add to the marinade. Seal the bag and turn to coat. Refrigerate for 30 minutes to eight hours, turning occasionally. Discard the marinade.
Preheat the grill on medium-high.
Grill the chicken for 6 to 7 minutes on each side, or until no longer pink in the center.
To serve, garnish with the lemon slices and sage leaves.