À l'ancienne is French for "In the ancient style." Traditionally this referred to a variety of classical grand dishes, garnished with cockscombs and truffles, the sort of thing which might be served at a banquet. These dishes have largely gone out of fashion now and à l'ancienne more readily describes braised beef, quenelles, blanquettes and fricasées with a garnish of button mushrooms and small sliced onions or fish or poultry with a garnish of white wine sauce with mushroom caps and braised onions with heart-shaped croûtons.
