Heat a large skillet over medium-high heat.
Add the ground beef to the skillet and cook until browned, breaking it apart with a wooden spoon, about 5 minutes.
Drain excess fat from the skillet if necessary.
Add minced garlic and ginger to the beef, cooking for an additional 1-2 minutes until fragrant.
In a separate bowl, mix together the soy sauce, brown sugar, sesame oil, black pepper, and red pepper flakes (if using).
Pour the sauce mixture over the cooked beef, stirring well to coat evenly. Cook for another 3-5 minutes until the sauce is heated through and slightly thickened.
Stir in the chopped green onions, reserving a few for garnish.
Serve the ground beef over cooked rice or noodles, and sprinkle with sesame seeds and remaining green onions.