1. Light the grill or heat the broiler. Sprinkle the fish with 1/2 teaspoon salt and 1/4 teaspoon pepper. Overlap two of the grape leaves and put a piece of the fish in the center. Fold the bottom of the leaves over the center of the fish. Fold in the sides of the leaves like an envelope to enclose the fish. Fold the top of the leaves over so that the fish is completely covered by the grape leaves. Brush some of the oil over the packet to seal the leaves and keep them from sticking to the grill. Repeat with the remaining fish, grape leaves, and oil, making eight packets in all.
2. Grill or broil the fish packets, turning once, until just done, about 8 minutes in all for 3/4-inch-thick fillets.
3. Meanwhile, melt the butter in a small saucepan. Stir in the garlic, lemon zest, capers, lemon juice, parsley, and 1/8 teaspoon each salt and pepper. To serve, spoon the sauce over the grape-leaf packets.
Fish Alternatives: Other lean, white fish fillets, such as rockfish, haddock, pompano, or striped bass, can be substituted here, but be sure to remove the skin.
Wine Recommendation: The aggressive flavors and acidity of sauvignon blanc are ideal with the taste of the grape leaves and the acidity of the lemon and capers. Try a bottle from the north of Italy.