Korean-Chinese fish cake soup over noodles (ool myun)

This is a dish from my childhood, one that I did not realize was part of a Korean-Chinese fusion (see http://en.wikipedia.org/wiki/Korean_Chinese_cuisine) until many years later. 

This is one of my childhood favorites, with its delicate flavor and contrasting textures.  Sauté bite-sized pieces of 1/2 lb beef chuck (see Note below) in a little oil.  Season with black pepper and salt.  When browned, add 1 medium onion (rough-cut) and sauté.  Add 6 cups of hot water to the pot, bring to a boil, reduce to a simmer, and add about 1.5 to 2 Tbsp Korean beef bouillon (sogogi dashida), and a dash of garlic powder and black pepper to taste.  Add 1 medium to large potato (here, Idaho), peeled and cut into 1.5” dice.  Then add a variety of sliced Japanese fish cakes (about 2 -3 oz), ranging from kamaboko to small spheres, to the pot.  Cover and let simmer until the potato is tender (about 10 mins), then stir in a potato starch slurry (about 1.5 tsp potato starch diluted with 1 Tbsp room temperature water) to thicken. Finally, pour a thin stream of egg whites from 3 eggs into the broth, creating ribbons in the soup.  

Separately, cook udon noodles until al dente, drain, and set aside.  Serve by placing some noodles in a bowl, then pouring the soup mixture overtop.  Garnish with chopped scallions. This recipe is from my mom, with modifications (addition of onion and a wider variety of fish cake).  (Mar. 2015)