Cook the linguine according to package instructions until al dente. Once cooked, drain it well and set aside.
In a large skillet over medium heat, add the ground beef and cook until browned and fully cooked through. Drain any excess fat.
Introduce minced garlic into the skillet and sauté for about one minute until fragrant. Stir in brown sugar, beef broth, soy sauce, hoisin sauce, ginger, black pepper, and optional red pepper flakes.
Mix cornstarch with water until smooth to create a slurry. Pour this mixture into the skillet and stir continuously until it thickens up nicely, about two to three minutes.
Add the drained linguine pasta into the skillet with the sauce mixture and gently toss everything together.
Garnish with sliced green onions on top before serving hot.