To make fish cake skewers: Fold the fish cake sheet lengthwise into halves or thirds. Insert a wooden stick through the top of the folds and twist as you skewer them, about 2-3 times per sheet. Set aside.
To make dashi soup base: In a large soup pot, combine a piece of dried sea kelp with 8 cups of water and bring to a boil over medium-high heat. Remove and discard the kelp, then take the pot off the heat. Add katsuobushi to the kelp stock, cover with a lid, and let sit for 5 minutes. Strain out the katsuobushi, keeping the stock.
Add sliced kimchi and kimchi juice to the stock and bring to a boil. Reduce heat and simmer for 5 minutes. Then, add the fish cake and simmer for another 5 minutes. Season the soup base with tsuyu, salt, and pepper to taste.
For udon Noodles: Boil water in a separate pot (The water should be enough to cover the noodles). Turn off the heat, add frozen udon noodles, and let them soak for 2 minutes. Once loosened, gently separate the strands.
To serve: Place a portion of noodles in a bowl. Pour the kimchi dashi soup over the noodles, adding fish cake pieces or skewers. Garnish with thin slices of Asian leek or chopped green onions and crumbled dried seaweed snack. Top with freshly cracked black pepper. Serve hot and enjoy!