I offer grilled onions, just oil water and onions. I want to offer something with a little more “wow” to it   ….

Water …!!  just a though & suggestion to try.     Use a spray bottle of water and add different flavorings & liquid smoke (small amount) and mist several times while cooking.  I use to do this with chicken when using a gas grill.   Everyone like them and the smoke flavor was not overpowering or bitter.