Begin by bringing a large pot of salted water to a rolling boil over high heat. Add linguine and cook according to package instructions until al dente, usually about 8-10 minutes. Once done, drain the noodles well and set them aside.

In a large skillet, heat over medium heat and add ground beef. Cook for about 5-7 minutes, stirring occasionally, until the beef is browned and fully cooked. Drain excess fat from the skillet.

Add minced garlic to the skillet with the cooked ground beef. Sauté for approximately 1 minute or until the garlic is fragrant and golden.

Stir in brown sugar, beef broth, soy sauce, hoisin sauce, ground ginger, and a pinch of red pepper flakes if desired. Let this mixture cook for about 2-3 minutes.

In a small bowl, whisk together cornstarch and water to form a slurry. Pour it into the skillet and stir continuously for 2-3 minutes until the sauce thickens.

Add the drained linguine to the skillet, tossing well to coat the noodles in the sauce. Cook everything together for about 1 minute to heat through.

Remove the skillet from heat. Serve the noodles hot, garnishing each bowl with sliced green onions.