"This lamb chop is delicious."
Translation:Cette côte d'agneau est délicieuse.
She is right, considering the size of "un agneau". But "une côte d'agneau" is perfectly correct.
"Une côte" is used with bigger animals: "une côte de boeuf/de veau", notably.
By the way, you probably know it, but the suffix -ette is often used for smaller variants of the main thing: une fille/fillette, une table/tablette, etc.
Lamb and sheep are eaten throughout Europe, the Americas, the Middle East, Australia, New Zealand, and many parts of Africa. It's not nearly as popular here in the US as beef, pork, and poultry, but it's been a basic part of much of the world's diet for about as long as humans have been domesticating animals.