싶은 건

what ... want

→ 싶다
phrase Rare #17,015
what ... want 건 is a shortened form of 것은, meaning “the thing that” or “what.” The subject who wants something is usually understood from context.
KO: 네가 하고 싶은 건 뭐야?
EN: What do you want to do?

너 에게 묻고 싶은 건 네가 내 아버지를 잡았는데 목적이 무엇 이냐?

What I want to ask is, why did you capture my father?

— 너자 2 (2025)