In a pot, combine water and dried kelp. Simmer for 10 minutes over medium heat. After 10 minutes, add the dried bonito flakes. Once it comes to a simmer, turn off the heat then steep for 15 minutes. Strain well then set aside.
Bring the dashi broth to a simmer over medium heat. Using a fine mesh sieve, dissolve the red miso into the broth. Next, add mirin and mushroom powder.
Carefully add the udon noodles. If using frozen udon noodles, parboil it for 1 minute to loosen the noodles.
Toss in the white part of the scallions then bring it to a simmer. Add the toppings including fish cakes, tofu skin, scallions, garlic chips, sliced hot pepper, sauteed oyster mushrooms, or your favorite toppings!
Crack an egg in the center then simmer for 1 to 2 minutes or until the egg has set. Garnish with ground black pepper.
Serve and enjoy!
