Bring a large pot of salted water to a boil and cook the linguine according to package directions. Drain and set aside.
In a large skillet over medium-high heat, cook the ground beef until browned and fully cooked. Drain excess grease if necessary.
Add the minced garlic and cook for 1 minute until fragrant.
Stir in the brown sugar, beef broth, soy sauce, hoisin sauce, ground ginger, black pepper, and red pepper flakes. Mix well.
In a small bowl, whisk together the cornstarch and water until smooth.
Pour the cornstarch slurry into the skillet and stir continuously. Simmer for 2–3 minutes until the sauce thickens.
Add the cooked linguine to the skillet and toss until all noodles are evenly coated with the sauce.
Cook for an additional 2–3 minutes, allowing the noodles to absorb the flavors.
Garnish with sliced green onions and serve immediately.