"Black butter." Butter heated until dark brown, with a few drops of vinegar and sometimes capers added, served especially with skate and brains.
Compound butter. Made from softened butter mixed with aromatics or herbs or with a flavour complimentary to the central dish with which they will be served. This might, for example, mean mixing butter with garlic or tarragon, or with an essence derived from crayfish or lobster. Sometimes the butter is heated.
"Toasted butter." Butter heated until dark brown, with a few drops of vinegar and sometimes capers added, served especially with skate and brains.