Bring a large pot of salted water to a rolling boil. Add spaghetti and cook until al dente, about 8-10 minutes. Reserve 1/4 cup pasta water before draining.

In a large skillet, heat neutral oil over medium-high heat. Add ground beef and break it up. Cook for 5-7 minutes until browned.

Reduce heat to medium. Add minced garlic and grated ginger. Sauté for 1 minute until fragrant.

Pour in soy sauce, chili oil, brown sugar, and rice vinegar. Stir and let simmer for 2-3 minutes.

Add drained spaghetti to the skillet. Toss until noodles are well-coated. Add reserved pasta water if sauce is too thick.

Drizzle sesame oil over the spaghetti. Stir in chopped green onions and optional sesame seeds.

Plate the spaghetti while hot, garnishing with extra green onions or sesame seeds if desired.