In a small bowl, whisk together soy sauce, broth, rice vinegar, brown sugar, and cornstarch. Set aside.
In a large skillet, brown ground beef over medium heat, seasoning with salt and pepper.
Reduce heat to medium-low and add garlic and ginger to pan. Let cook until fragrant, just 2-3 minutes.
Pour sauce into pan and stir. Let simmer and thicken, 1-2 minutes.
Stir to coat ground beef with sauce. Add green onions and cook briefly to wilt, about 2 minutes.
Serve over white rice with steamed vegetables, if desired.