Preheat the grill to 400 degrees F
Tear of a large piece of parchment paper Layer the potato slices in center of parchment paper
In a medium bowl, toss the cherry tomatoes and olives with lemon juice, olive oil, salt and pepper to taste. Pat the fish fillet dry and season both sides to taste with salt and pepper.
Place the fish fillet on top of the sliced potatoes and gently pour the tomato-olive mixture on top. Add a splash of white wine. To seal, fold each corner into the center, twist, and secure with twine. It is important to make sure the parchment is tightly sealed so no steam escapes during cooking.
Place the parchment packet on the grill. You will know its ready when the Fish flakes easily with a fork.