Korean spicy beef and radish soup

We made this soup loosely based on Maangchi’s recipe: https://www.maangchi.com/recipe/radish-soup However, we made so many modifications (including doubling the original recipe) that I’m rewriting our whole recipe here.  First, cut 1 lb skirt steak (preferably trimmed of fat) into bite-sized pieces, then marinate in the following seasonings for about 15-20 mins (see Note below):  1 ½ Tbsp hot pepper flakes (down from 2 Tbsp in the doubled, original recipe), 3 Tbsp fish sauce (down from 4 Tbsp), 2 Tbsp sesame oil, 2 tsp salt, and 4-5 cloves minced garlic.  Second, while the meat is marinating, peel one large (about 1 ½ lb, but it can be up to 2 lb) Daikon radish and then cut into ½ inch thick penny slices (if the daikon is fairly narrow in diameter) or into half-moon slices (if the diameter is thick); as most Daikon are cone-shaped, I often cut penny slices along the bottom half and then half-moon slices for the upper half of the radish.  Third, heat a large Dutch oven on medium-high heat, and lightly coat the bottom with 1 tsp neutral oil, such as grapeseed or canola. Add the marinated beef and sauté on medium heat until most of the pink color is gone.  Fold in the daikon slices, lightly coating them with the red-tinged oil.  Pour in 10 cups hot water, bring to a vigorous boil for about 10 mins, and then cover and reduce heat to a medium-low simmer until the daikon is fully cooked (about 30 mins).  Add 6 scallions, cut into 2-inch long straws, and then simmer, uncovered, for another 5 mins. Season to taste with salt and black pepper. Separately, chop 1 additional scallion and set aside. When ready to serve, garnish each serving with a sprinkle of chopped scallions. Serve with short-grain rice (we like Haiga, a type of brown rice that retains the rice germ but not the rice bran).  We often also serve with egg white omelette on the side for contrasting texture and as a mild foil for the spicy soup.  (May 2017)

Note: For a lower sodium version, we recommend adjusting the marinade for 1 lb beef as follows: 1 Tbsp red pepper flakes, 1 to 1 ½ Tbsp fish sauce, 1 ½ to 2 Tbsp sesame oil, ½ tsp salt, and 4-5 cloves minced garlic. For the soup, you can start by adding 7 cups of water, taste when the soup is done, and incrementally add up to 3 more cups water until you achieve the right level of salt for yourself.