Mince the garlic and ginger and slice the green onions; set aside.

Heat a large skillet over medium-high heat until a drop of water sizzles, about 2 minutes.

Add vegetable oil and then ground beef in a single layer; let it brown undisturbed for 2–3 minutes.

Break up the beef and continue to cook until no pink remains, about 5–7 minutes total.

Tilt the pan and spoon out excess fat, leaving a thin coating in the skillet.

Reduce heat to medium and add garlic and ginger; cook, stirring constantly, for 30 seconds to 1 minute until fragrant.

In a small bowl, whisk together soy sauce, brown sugar, water, and red pepper flakes until sugar dissolves.

Pour the sauce into the skillet and increase heat to medium-high; cook, stirring constantly, for 2–3 minutes until sauce thickens and coats the beef.

Remove from heat and stir in sesame oil; season with salt and pepper to taste.

Transfer to a serving plate and garnish with sliced green onions and sesame seeds.