Cook the noodles: Bring a large pot of salted water to a boil. Add the Spaghetti noodles and cook according to the package instructions until al dente. Drain and set aside.

Make the sauce: In a small bowl, mix soy sauce, oyster sauce, brown sugar, cornstarch, water, and beef broth. Set aside.

Stir fry the ground beef: Heat a large skillet or wok over medium-high heat. Add the ground beef in a single layer and sear for 1-2 minutes per side until browned. Work in batches if necessary to avoid overcrowding the pan.

Cook the aromatics: Add the minced garlic and ginger to the ground beef and stir fry for 30 seconds until fragrant. Toss the cooked noodles into the ground beef.

Combine the sauce: Pour the prepared sauce into the skillet over the noodles and the cooked beef. Toss to coat well to ensure the noodles are fully coated in the savory sauce.

Serve and garnish: Add salt and black pepper to taste. Remove from heat and garnish with sliced green onions, sesame oil, red pepper flakes (if using), and toasted sesame seeds. Serve immediately and enjoy your Mongolian Beef Noodles!