Common sole is a flatfish native to the Mediterranean Sea and the Atlantic Ocean. It prefers shallow waters where it can semi submerge itself in the sandy or muddy seabed. Its upper body is brownish grey, its underside is white and it grows to a length of a little over 2 feet.
Dover sole, named after the British fishing port which landed large quantities of sole in the 19th century to supply the London market, is admired for its buttery taste and firm fillets that hold together well during cooking. It’s popularity in European continental cuisine eventually caused overfishing and some responded to the scarcity by marketing other flatfish, most often species of flounder, as sole (grey sole, lemon sole and petrale sole all are in fact flounders).
Because of its prestige, the name “Dover sole” was appropriated to a name a totally different eastern Pacific species that has thinner, less firm fillets and sells for less money. Despite what labels your fish market may employ, in the United States most commercially fished species of flatfish are flounders. Sole is caught in European waters that range from the Mediterranean to the north of Scotland and the south of Norway. The North Sea and the Bay of Biscay are the prime sole fishing grounds.
In 2010 Greenpeace International added the common sole to its red list of fish sold in supermarkets that have a high risk of being sourced from unsustainable fisheries. The Monterey Bay Aquarium Seafood Watch (which “helps consumers and businesses make choices for a healthy ocean”) lists Pacific sole (or should we say flounder) as a “best choice” and sole caught in British Columbia, Canada as a “good alternative.”