Seongsu Japanese restaurant: cold udon and chicken tempura at Kosi

Today, I finally took a little trip to Seongsu-dong again. Food comes first! I had originally planned to go to a pasta place, but it was so hot that I visited Kosi, a great tonkatsu spot near the station.

Kosi Seongsu Branch: the basics

• Hours 11:00–21:00
• Break time 15:00–17:00
• Parking for about 2 cars in front of the restaurant
• Download a Naver coupon for complimentary tempura, croquette, and more

This is a place I used to visit often in the neighborhood, and I came back after visiting Seoul Forest last week because it was so good. There happened to be a discount too, so that was nice💕

Waiting and seating at Kosi Seongsu

There were about three parties waiting both on my last visit and this one. Has word already gotten out that it’s good... wow. (For same-day waiting, you can only add your name to the list / no Catchtable.)

You can order from the table. Each seat has shichimi (Japanese seven-spice blend), a sesame grinder, and salad dressing.

There’s a cutlery compartment under the table!

There are around 20 table seats.

There are also about eight window and counter seats, so you can eat alone too.

Tonkatsu, udon, and soba menu

Kosi’s menu has tonkatsu, udon, and soba. ✔️ Tonkatsu set meals come with udon, while ✔️ udon set meals come with tonkatsu.

Half-and-half tonkatsu and cold noodle dishes

Half-and-half tonkatsu

The basic sides are danmuji (pickled yellow radish) and kkakdugi (cubed radish kimchi), plus soup, salt, wasabi, and cabbage salad. The salad dressing is on the table, and it tastes even better with freshly ground sesame mixed in❣️

I really loved this cheese cutlet—the flavor was clean, and the cheese stretched and stretched, haha.

Bukkake udon

Next came the bukkake udon. It had thick udon noodles, shrimp and kabocha tempura, a plump inari sushi, scallions, radish, tempura crumbs—and, most importantly, tsuyu dipping sauce.

Just drizzle on the tsuyu to your taste. It seems really salty at first, but with the noodles, the seasoning is just right.

Zaru soba

My favorite, zaru soba. The portion is pretty big..?

I skipped the scallions and ate it with just radish and wasabi. I thought there might not be enough dipping broth, but it was exactly right.

Tori ten bukkake udon

Tori ten bukkake udon.

A little drizzle of broth for this one too. They say the udon is made the traditional way, and the noodles are so wonderfully springy! Rather than the familiar broth of packaged udon, it’s intensely rich—almost like sukiyaki? It’s somehow addictive, hehe. I absolutely love pan momil (cold buckwheat noodles), but at Kosi, udon wins for me every single time!!!

The chicken tempura that came with it was pure art. The coating was crisp while the meat inside was tender—so deliciousㅠㅡㅠ I always ordered the udon with tempura, but I think this will be my go-to from now on!!!

My overall take after two visits

I’ve visited Kosi Seongsu Branch twice, and the line out front kept getting longer each time.. The tonkatsu is crispy, the tempura is crispy, and the udon noodles are seriously high quality!!!!

Kosi also has a Gil-dong branch, which I often ordered from for delivery, but the Seongsu branch is fairly new, so I don’t think it is hugely crowded just yet. This is truly a place that wins on flavor, so I think it will become even more popular. I recommend doing an early weekday opening run and trying it before it gets busy👍