Prepare all ingredients by slicing the onion, bell pepper, and carrots. Mince the garlic and chop the green onions.
Heat vegetable oil in a large skillet or wok over medium-high heat. Add sliced onion and cook for 2 minutes until soft. Push onions to the side and add ground beef. Cook for 5-7 minutes until browned.
Add minced garlic, bell pepper, and julienned carrots. Stir-fry for 3-4 minutes until vegetables are tender-crisp. Pour in soy sauce, brown sugar, oyster sauce, ground ginger, and black pepper. Mix well.
Prepare egg noodles according to package instructions. Drain and set aside.
Add cooked egg noodles to the skillet with beef and vegetables. Toss gently to coat noodles in sauce. Cook for an additional 2-3 minutes until heated through. Garnish with chopped green onions before serving.