Cook the noodles according to package instructions. Drain and set aside.

In a large skillet, heat the vegetable oil over medium-high heat. Add the diced onion and sauté for 2-3 minutes until softened.

Add the minced garlic and cook for an additional 30 seconds until fragrant.

Add the ground beef to the skillet, breaking it up with a spatula. Cook until browned and fully cooked, about 5-7 minutes.

Stir in the sliced bell pepper and julienned carrots, cooking for another 3-4 minutes until the vegetables are tender.

In a small bowl, mix together the soy sauce, brown sugar, hoisin sauce, ground ginger, and black pepper. Pour this sauce over the beef and vegetable mixture, stirring to combine.

Add the cooked noodles to the skillet, tossing everything together until the noodles are well coated in the sauce. Cook for an additional 2-3 minutes to heat through.

Serve hot, garnished with sliced green onions.