How to do research to write characters from a different culture?

Let's say I'm French and I'd like to write a Korean character.

How can I build their personality traits, values, etc. in a realist way?

I'm afraid to end up with a character only superficially Korean : eating kimchi and listening to k-pop but without any depth or realism.

I'm especially interested on how to do research in this situation, and then how to organize and use the results. Researching a culture's cooking/music/clothing is easy but psychology/values/feelings are complicated.

I can't move to Korea or enroll in a Korean history class in my area.

Should I watch/read Korean things to form a first impression of how Korean directors/writers see the world? Should I write something and then find a Korean to proof-read it?

Is there a way to find good books/documentaries on a country's culture? (And be certain it's not a collection of stereotypes even if you don't know anything about it beforehand)