Cook egg noodles according to package instructions; drain and set aside.
In a bowl, mix soy sauce, oyster sauce, and cornstarch; set aside.
Heat sesame oil in a large pan over medium-high heat.
Add beef tips to the pan; season with salt and pepper.
Sauté beef for about 5-7 minutes until browned.
Add minced garlic, broccoli, and bell pepper to pan; stir-fry for 3-4 minutes.
Pour sauce mixture over the beef and vegetables; stir well.
Add cooked noodles to the pan; toss to combine.
Cook for an additional 2-3 minutes to heat through.
Serve hot, garnished with chopped green onions.