Place beef pieces into a bowl and add salt, black pepper, cayenne pepper, and paprika. Toss very thoroughly until meat is evenly coated. Let sit at room temperature for about 20 minutes before browning, or place in the fridge until needed.
Add oil to a heavy-bottomed pot, and heat on high until oil is shimmering. Add beef in a single layer, and sear until a nice brown crust forms, 3 to 5 minutes.
Turn beef over, and let other side cook about 2 minutes. The second side will not brown like the first, but that’s okay. Turn heat down to medium-high; remove beef to a bowl and set aside.
Add onions, celery, peppers, and minced garlic to the pot, and cook, stirring, until onions begin to turn translucent, 3 to 5 minutes.
Add beef back in along with any accumulated juices. Add soy sauce, Worcestershire sauce, granulated garlic, water, and beef bouillon paste. Stir and wait for soup to come to a simmer. Lower heat to medium-low and simmer until the meat is very tender, 60 to 90 minutes.
Before serving, taste and adjust with more salt or soy if needed. Keep soup on low heat until ready to serve.
Bring a large pot of lightly salted water to a boil. Cook spaghetti in the boiling water, stirring occasionally, until tender, about 12 minutes. Drain, and divide evenly between 4 large soup bowls.
Ladle hot soup over noodles, and garnish each bowl with a hardboiled egg, hot sauce, and sliced green onions.