Sieve the flour, salt, and fennel into a food processor bowl.
Mix at low speed with a dough hook.
Add egg whites for three minutes then slowly incorporate water while increasing speed.
Roll the dough into a tight ball on a floured surface.
Wrap in cling film and rest for 20 minutes at room temperature.
Sauté sliced shallots in 60g butter until opaque.
Stir in thyme, bay leaf, and peppercorns.
Add vinegar and boil until liquid has evaporated completely.
Add white wine and reduce until evaporated.
Add garlic and cream, bring to a boil, then add water.
Whisk in 210g chilled cubed butter piece by piece over low heat.
Season with salt, cayenne, and lemon juice.
Prepare tomatoes by blanching, peeling, seeding, and dicing.
Mash anchovies into a paste and chop the parsley.
Roll a piece of salt crust into a 32cm x 20cm rectangle about 7.5mm thick.
Place sea bass in the center and cover with a second layer of pastry.
Seal edges with water and trim, leaving a 1cm border.
Decorate pastry with fish details and brush with egg wash.
Bake in a preheated oven at 220°C for 20 minutes.
Mix tomato, anchovy, and parsley into the warm butter sauce and serve.