This is a traditional soup that is eaten on New Year's day. It makes a nice, soothing breakfast soup that I like to serve with kimchi. For a variation, try this duk mandu guk recipe, which has dumplings.
2 lb white ready sliced rice cake, available in the refrigerated/frozen section of Korean grocers
1/2 lb beef (flank steak)
dash of soup soy sauce (guk ganjang 국간장)
5 cloves garlic, minced
3-4 bunches of green onion, chopped
1 tbsp salt
5 sheets of dried seaweed (gim)
Soak the sliced rice cake in cold water and let sit for l/2 hours or so.
Soak beef for 10-15 min to get blood out and place in a pot with 8-9 cups of water. Boil until the meat get tender, approximately l/2 hr.
Take out the beef and let it cool. Slice into thin strips, approx. 1 1/2" x 1/2". Season with the beef strips with a dash of soup soy sauce (guk ganjang 국간장), 1 tsp salt, and a pinch of the minced garlic and a pinch of chopped green onions. Set the seasoned beef strips aside and strain the beef broth -- also set this aside.
Beat egg whites and yolks separately, and add pinch of salt and pepper to both. Pour the egg whites into a heated frying pan. The goal is to have thin sheets of egg. Repeat with the yolks. Cut the thin egg sheets it into narrow matchstick-style slices.
Roast the dried seaweed sheets over a burner (a few seconds on each side, until it changes from dark green/black to light greenish) or put into a toaster oven. Slice the roasted seaweed into thin strips as well, or crush with your hand. Put into a serving dish.
Pour back the beef broth into the pot and bring it to a boil. Add another dash of soup soy sauce (guk ganjang 국간장) and salt and pepper to taste. When the broth starts to simmer, add the rice cake. Return to a boil. You're ready to start serving.
For each serving, get a large bowl. Scoop up some soup with enough rice cakes, garnish with seasoned beef strips, yellow and white egg threads and chopped green onions. Serve the roasted seaweed at the table for people to individually add into their bowl throughout the meal.