Delicious food in
Why locals love it
Far from fancy Ariran is the closest to Korea you can get in Tallinn. Run by an older guy and his wife (?) who don't speak much Estonian it serves authentic food accompanied by a bit awkward service. Dishes almost always come in portions you won't be able to finish if you follow the owner's advice. Done that several times. Try kimchi.
Why you should visit it
You should look this little joint up mainly to expand your horizons, in both getting further away from the central Tallinn and in culinary experiences outside your usual habits. They even carry Korean beer and several kinds of the infamous Soju (pretty nasty drink that tastes like vodka diluted with water). Complex lunch is a good way to start.
Keep an open mind and be willing to experiment with unexpected tastes. P.S. You'll find the toilet key hanging on the wall.