Finely chop and mix the thyme leaves, parsley and lemon zest. Scale and gut the sea bass and stuff the cavity of the fish with the herb mixture plus the smashed garlic clove.
Whip the egg whites and mix gently with both the rock salt and table salt until sticky. If necessary add some water.
Boil the lettuce leaves in water and pat them dry. Spread two-thirds of the salt mixture on the base of an oven-safe dish or skillet, brush the fish with olive oil and cover with the lettuce leaves to protect the fish.
Lay the fish on the salt bed and cover it completely with the rest of the salt mixture. Press the crust firmly and make sure no spots are left without it.
Bake at 180°C for 25 minutes.
Carefully break the salt crush, remove and place the fish meat onto a serving plate avoiding bones and fins.
Season with a drizzle of extra virgin olive oil.