How to Make It
In a bowl, combine the melted butter with the garlic, shallots, ground fennel seeds, lemon zest, orange zest, tarragon, black pepper and thyme.
Preheat the oven to 300°. Brush a large glass or ceramic baking dish with olive oil. Lightly season the salmon fillet with kosher salt. Spread half of the seasoning mixture on the skinned side of the fish. Place the salmon skinned side down in the baking dish and fold the thin tail end under itself to make the fillet an even thickness. Stir the cayenne pepper into the remaining seasoning mixture and spread it over the salmon. Let the salmon stand at room temperature for 20 minutes.
Carefully pour the orange juice into the baking dish and cover the baking dish tightly with aluminum foil. Bake the salmon for about 35 minutes, until it is barely opaque in the center.
Sprinkle the salmon with the lemon juice and sea salt and serve.
The seasoning mixture can be refrigerated overnight.