Preheat the oven to 350F. If you're making potatoes, start those now by liberally covering with olive oil and a little bit of salt and placing in their own quarter sheet in the oven. Pat your fish dry on both sides with a paper towel and add flaky sea salt to both sides. Lay out 2 of your parchment papers next to each other on a single baking sheet. Place the filets face up on each piece of parchment paper and then lay your lemon slices on the fish. Next, place the tomatoes face up on and around the fish and then do the same with the olives and finish by sprinkling each piece of fish with parsely.

Crack your egg in a small bowl and whisk until its albumen and yolk are fully incorporated. With a light brush, brush the egg wash 1" all the way around from the edges of the parchment paper on all 4 sides. Do this on both parchments and then lay the remaining two parchments on top of the first two to cover the fish. Crimp the edges all the way around so as to fully encapsulate the fish and create an air tight pocket. The egg wash will cook in the oven sealing the edges entirely and allowing the fish to cook from the steam of the ingredients incorporated. Cook for 25-30 minutes and serve on a warm plate with the potatoes. Soave, Gavi di Gavi & Vermentino are wonderful pairings for this.