I am a local mum and Korean.
In New Malden, Jin Go Gae, Sorabol or You Me are probably a safe bet. Locally I would recommend Hana - they have very good Jeon (pancakes), BBQ dishes and Jjigae (spicy soups).
If you would like to try gastronomic/fusion style Korean food, I heard a new restaurant just opened on Kingly street called Jinjuu is pretty good.
I hope this helps!