This place has been around for quite some time despite Seoul's penchant for updating and changing pace of life.
The restaurant BaetGotDong (뱃고동) is known for its spicy stir-fried octopus dish, but a lot of customers also order the batter-fried octopus dish as well to complement their meals.
You can also decide to have fried rice with the remaining octopus pieces and sauce at the end. Here's a short video clip of the making done solely by the waiter or waitresses of the restaurant:
The best part perhaps is that they have Febreze available for you when you pay at the counter for your meal.