Preheat the oven to 450°.
Using a mandoline or the slicer side of a box grater, very thinly slice the potatoes, zucchini and onion.
In a large bowl, mix the potatoes, zucchini and onion with the tomatoes, wine, EVOO, half the parsley, the garlic and oregano; season with salt and pepper.
Cut 4 large sheets of parchment paper, each about 12 by 16 inches. Arrange 1 sheet with the short side in front of you. Place a quarter of the potato mixture horizontally along the bottom half. Top with a fish fillet [1, above]; season and top with 1/4 tsp. crushed red pepper and a quarter of the lemon zest. Add a pat of butter and some of the remaining parsley. Fold the parchment over the fish [2, above], then roll and crimp the edges to seal along one side so it looks like an empanada or turnover [3, above]. Transfer the packet to a baking sheet. Repeat with the remaining ingredients.
Bake until the fish is just opaque in the center and the potatoes and zucchini are just tender (a knife will easily slide into the fish when pierced through the paper and will be hot to the touch), 17 to 18 minutes. Using a large spatula, carefully transfer the packets to shallow bowls or plates. Open carefully (lots of steam will be released).