Cook the lobster for four minutes in the boiling nage. Remove it from the heat and let it cool in the liquid for five minutes.
Reduce the sauce Américaine to half its volume in a heavy saucepan. In a separate saucepan boil the white wine, shallots, lemon juice, tarragon, chervil, salt and pepper, until it is reduced to a moist purée (there should be about two t