Begin by bringing a large pot of generously salted water to a rolling boil, allowing the salt to enhance the pasta's flavor. Add the spaghetti and cook for 8–10 minutes, or until al dente, ensuring it has a slight bite. Before draining, reserve 1/4 cup of the pasta water.

In a large skillet or wok, heat 1 tablespoon of neutral oil over medium-high heat. Once hot, add the ground beef, breaking it apart with a wooden spoon. Cook for 5–7 minutes until the meat is thoroughly browned and no longer pink. Drain any excess fat if desired.

Lower the heat to medium and add the minced garlic and grated ginger to the skillet with the browned beef. Sauté for about 1 minute until the garlic becomes fragrant and slightly golden.

Stir in the soy sauce, chili oil, brown sugar, and rice vinegar, mixing well to combine all the flavors. Allow the sauce to simmer for 2–3 minutes, thickening slightly.

Add the drained spaghetti directly into the skillet, tossing gently to ensure each strand is coated. If the sauce seems too thick, gradually add the reserved pasta water.

Remove the skillet from the heat and drizzle 1 teaspoon of sesame oil over the pasta. Toss in the chopped green onions and optional sesame seeds.