Living as a mostly-vegetarian in Korea, I know it can be pretty hard to find vegetarian food. It was a great disappointment to me that even the vegetable mandu (dumplings) all contained meat and my city of Daejeon only boasts 2 vegetarian restaurants. On my latest trip to Seoul, I made sure to visit some of these places and the only thing I have to say is that the people there are REALLY nice and they have the plumpest, juiciest, vegetarian mandu (12 for 6,000 won). My friend also ordered their bibimbap for 6,000 won and I had one of their noodle soups for 5,000 won. I would definitely go back again, even though their menu appeared to be predominately drinks.
The no onion and garlic rule is a plus and it was really easy to find. :)Pros: reasonable prices, friendly, bilingual staff, DELICIOUS mandu
Cons: small, simple menu