This article is addresses the theoretical issues related to the teaching of Greek idioms in the context of a foreign language. The author claims that idioms are highly pervasive in the Greek language, which makes it essential to find an appropriate teaching strategy to teach Greek learners. The author suggests a concept-oriented textbook arranged around universal and culture-specific metaphors and/or metonymies accompanied by the necessary morphosyntactic cues and information on potential constraints on use. The notions of frequency, compositionality and register are also regarded as essential for teaching Greek idioms.