Preheat your oven to 450°F (230°C). Line a baking sheet with parchment paper.
In a large bowl, combine the coarse sea salt and egg whites. Mix until the salt is evenly moistened and resembles wet sand.
Place half of the salt mixture on the prepared baking sheet, shaping it into a bed for the fish.
Stuff the cavity of the fish with lemon slices and fresh herbs. Drizzle the fish with olive oil and season with black pepper.
Place the fish on top of the salt bed. Cover the fish completely with the remaining salt mixture, pressing it down to form a solid crust.
Bake in the preheated oven for 25 to 30 minutes, or until the fish is cooked through and the salt crust is hard.
Remove the fish from the oven and let it rest for 5 minutes. Carefully crack open the salt crust and remove the fish. Serve with your favorite sides.