Fill a large pot with lightly salted water and bring it to a boil. Add the spaghetti and cook, stirring occasionally, for about 12 minutes until it's al dente, tender but still firm. Once done, drain the pasta and rinse it under cold water to halt the cooking process. This ensures the noodles maintain their perfect texture and don't become overcooked. Set the pasta aside until ready to use.
In a large skillet, break up the ground beef over medium-high heat and cook for about 4 minutes, stirring occasionally. Once the beef starts to brown, add the minced garlic and cook for an additional minute, allowing the flavors to meld. Drain any excess grease to keep the dish lean and flavorful before proceeding.
Return the cooked beef to the skillet and stir in the ginger, brown sugar, soy sauce, hoisin sauce, beef broth, vinegar, and crushed red pepper flakes. This blend of ingredients will create a rich, flavorful sauce that complements the beef, adding depth and a perfect balance of sweetness, saltiness, and spice.
In a small jar, combine the cornstarch and cold water. Secure the lid and shake vigorously until the mixture forms a smooth, thick slurry. Pour this slurry over the beef mixture, stirring it in to thicken the sauce and give it a creamy, velvety texture that coats the beef and noodles beautifully.
Cook the mixture over medium-high heat for about 3 minutes, or until the sauce thickens. Stir in the reserved spaghetti and cook for an additional 2 minutes, allowing the noodles to absorb the flavors. Turn off the heat and let the dish sit for 1 minute to allow the sauce to set and the ingredients to meld together.
Garnish each serving with a sprinkle of chopped green onions and toasted sesame seeds, adding a burst of freshness and a subtle crunch to enhance the dish’s flavor and texture.