Preheat a gas grill over medium-high heat to about 400 degrees. Meanwhile pound chicken to an even thickness using the flat side of a meat mallet.
In a small mixing bowl whisk together hoisin sauce, soy sauce, rice vinegar, ginger, garlic, sesame oil, and Chinese Five Spice Blend.
Taste an season with salt and/or honey as needed. Pour half of the hoisin mixture into a separate small bowl.
Brush grill grates lightly with oil. Grill chicken 4 minutes then brush both sides with hoisin sauce mixture from one bowl.
Continue to grill on opposite side until nearly cooked through, about 3 minutes longer.
Brush both sides (using a clean basting brush) with remaining sauce and continue to grill about 1 minute longer, or until center reaches 165 on an instant read thermometer.