Cook the Spaghetti: Bring a large pot of salted water to a rolling boil. Add the spaghetti and cook according to package instructions until al dente, about 8-10 minutes. Reserve 1/4 cup of pasta water, then drain and set aside.

Brown the Ground Beef: In a skillet, heat 2 tablespoons of neutral oil over medium-high heat. Add ground beef, breaking it apart. Cook until browned and fully cooked through, about 5-7 minutes. Drain excess fat if necessary.

Sauté Garlic and Ginger: Reduce heat to medium, add minced garlic and grated ginger to skillet with beef. Sauté for about 1 minute until fragrant and garlic softens.

Mix in the Sauce Ingredients: Pour in soy sauce, chili oil, brown sugar, and rice vinegar. Stir well to combine. Let simmer for 2-3 minutes until slightly thickened and sugar dissolves.

Combine Spaghetti with the Sauce: Add drained spaghetti to the skillet and toss gently with beef and sauce. Add reserved pasta water as needed for desired consistency.

Finish with Seasonings: Drizzle sesame oil over spaghetti, toss to distribute flavor. Sprinkle with green onions and sesame seeds, mixing lightly to blend.