Prepare chicken by discarding any extra fat and cutting larger breasts (if using) through the thickness to make thinner cutlets. Place chicken in gallon freezer ziploc bag and set aside.

In a small bowl add the vinegar, olive oil, mustard, garlic, onion powder, thyme, basil, oregano, salt, and pepper and whisk to combine.

Set aside 3 tablespoons of marinade for basting later (optional). Pour remaining marinade over chicken and seal bag. Place bag in the refrigerator for at least 30 minutes or overnight (up to 24 hours).

To Grill: Preheat grill to medium or medium high. Arrange chicken on grill in a single layer and cook for about 5-6 minutes per side or until lightly browned and instant read thermometer registers 165 degrees F in the thickest part of the breast. For additional flavor, baste chicken with reserved marinade after flipping to second side.

To Broil: Preheat broiler to high. Adjust rack so chicken will be about 4 to 5 inches from the broiler. Arrange chicken on a broiler pan in a single layer and cook for about 5-6 minutes per side or until lightly browned and instant read thermometer registers 165 degrees F in the thickest part of the breast. For additional flavor, baste chicken with reserved marinade after flipping to second side.

Remove the chicken from the heat and tent with foil for 5-10 minutes before serving.