Bring a large pot of salted water to a boil and cook the noodles according to package instructions until al dente. Drain and toss with vegetable oil to prevent sticking.

In a large skillet, heat vegetable oil over medium heat. Add ground beef, breaking it apart with a spatula, and cook until browned, about 5-7 minutes. Drain excess grease.

Lower heat to medium-low, add minced garlic and grated ginger to the skillet, and sauté for about 1 minute until fragrant.

In a small bowl, whisk together soy sauce, brown sugar, and water. Pour into the skillet with the beef and aromatics and let simmer for 2-3 minutes.

Mix cornstarch with cold water in a bowl to create a slurry. Gradually add to the skillet while stirring, and cook for another 1-2 minutes until the sauce thickens.

Add drained noodles to the skillet and toss for 1-2 minutes until coated in the sauce.

Remove from heat and stir in sesame oil and half of the green onions.

Serve the noodles on plates, garnished with remaining green onions and sesame seeds if desired.