Bring a large pot of water to a boil and cook the spaghetti according to the package directions, about 10 minutes. Reserve ¼ cup (60 mL) of the pasta water, then drain the noodles and set them aside.
12 oz (340 g) dry spaghetti noodles, ¼ cup (60 ml) reserved pasta water
In a small bowl, mix the water and cornstarch together to make a slurry and set it aside.
2 tbsps (30 ml) water, 1 tbsp (8 g) cornstarch
Using the same pot, add the ground beef, sesame oil, and garlic. Cook over medium heat for 6 to 8 minutes, breaking up the meat as it browns. Drain any excess fat if needed.
1 lb (454 g) ground beef, 1 tbsp (15 ml) sesame oil, 5 cloves garlic
Stir in the tomato paste and ginger and cook for 3 minutes, letting the flavors blend.
1 tbsp (15 g) tomato paste, 1 tbsp (8 g) minced fresh ginger
Add the soy sauce, honey, beef broth, hoisin sauce, red pepper flakes, black pepper, and salt. Stir until everything is combined, then pour in the cornstarch slurry. Continue stirring until the sauce thickens slightly and coats the spoon.
½ cup (120 ml) low-sodium soy sauce, ¼ cup (60 ml) honey, ¼ cup (60 ml) low-sodium beef broth, 3 tbsps (45 ml) hoisin sauce, ½ tsp (~1 g) red pepper flakes, ½ tsp (~1 g) black pepper, ⅛ tsp (~ 0.75) kosher salt
Add the cooked spaghetti and reserved pasta water to the pot. Toss everything together until the noodles are coated. Remove from the heat and top with chopped green onions and sesame seeds before serving.
3 green onions, chopped (green parts only), 1 tbsp (9 g) sesame seeds