Toss beef with salt and pepper until evenly coated.

Heat vegetable oil on high heat in a Dutch oven. Brown the beef thoroughly on both sides, doing half at a time, and remove to a bowl. Turn off heat.

Add butter to Dutch oven, along with onions and a pinch of salt. Turn heat to medium-high, and cook, stirring, until onions turn golden, about 5 minutes.

Add flour, and cook, stirring, for 2 minutes more. Add garlic powder, beef base, and beef broth. Stir, and wait for broth to come to a boil. Add reserved beef back in.

Stir, and cover, and reduce heat to low. Simmer until meat is very tender, about 2 hours.

Use a strainer to remove beef to a bowl and reserve. Bring both to a boil on high heat, and add noodles. Cook, stirring, until the noodles are almost tender (about 30-60 seconds less than package directions. Stir in beef and reduce heat to low.

Once noodles are tender and beef is heated through, taste and adjust seasoning. Serve immediately topped with more freshly ground black pepper and green onions.