In a small mixing bowl, whisk together brown sugar, reduced sodium soy sauce, sesame oil, crushed red-pepper flakes, and ground ginger until well combined.

Heat vegetable oil in a large cast iron skillet over medium-high heat. Add minced garlic and sauté for 1 minute until fragrant.

Add ground beef to the skillet, breaking it apart with a spatula. Cook for 3-5 minutes until browned and fully cooked, draining excess fat.

Pour the sauce mixture into the skillet with the cooked beef. Stir in chopped green onions and let simmer for 2 minutes until heated through and sauce thickens.

Remove from heat and transfer the beef mixture into bowls. Garnish with additional green onions and sesame seeds. Serve immediately over steamed rice.