fresh fish, fileted, 1-2 pounds depending how many you are serving. I like sea bass; red snapper or flounder could work too.
or more or less basil pesto (vary to suit quantities of other ingredients)
lime juice, a few drops
whatever you have on hand of small fresh okra, mushrooms (cut in quarters if large), grape or cherry tomatoes in interesting colors, cubed summer squash, green onions, or other veg