In a medium bowl, whisk together soy sauce, beef broth, hoisin sauce, brown sugar, ground ginger, black pepper, and red pepper flakes. Set the sauce aside.

Bring a large pot of salted water to a boil. Cook linguine until al dente following package directions. Before draining, scoop out and reserve 1 cup of pasta water. Drain the pasta.

Heat a large skillet over medium-high. Add the ground beef and crumble it as it browns. Cook until there’s no pink left, then drain excess grease from the pan.

Add the minced garlic to the skillet and sauté about 1 minute until fragrant. Don’t let it brown too much.

Pour the prepared sauce over the beef and garlic. Let it simmer 2–3 minutes so flavors meld.

In a small bowl, whisk together the cornstarch and 2 tablespoons water to make a slurry. Stir the slurry into the skillet and cook 1–2 minutes until the sauce thickens and becomes glossy.

Add the drained linguine to the skillet. Toss gently to coat, adding reserved pasta water a tablespoon at a time if the sauce needs loosening. The goal is a clingy, saucy coating on the noodles.

Serve immediately, garnished with sliced green onions.