"soup of oseille, a sole quite simply cooked in a white wine sauce, a caneton à la presse"
Rumex scutatus
GNU Free Documentation LicenseRumex scutatus - Credit: Kurt Stueber, Wikimedia Commons

Oseille is sorrel. French cuisine uses French sorrel (Rumex scutatus) which is different from the Garden sorrel (Rumex acetosa) which grows wild in Britain.

Try this recipe for sorrel soup

Caneton à la presse (Vegetarians, look away now!), known in English as pressed duck, is duck served in a sauce made from its own blood and marrow, these ingredients being extracted using a specially designed press.