Lamb's fries are generally taken to be testicles, soaked, peeled and fried with onions, however there is some evidence that the term has been used for chopped liver.
'The west Somerset word-book: A glossary of dialectal and archaic words and phrases used in the west of Somerset and east Devon', 1886, by Frederick Thomas Elworthy, has; "FRY: The products of lamb's castration are called lamb's fries and are eaten with much gusto."