Cut the beef into 4 slices and place each piece between plastic wrap.
Pound beef into 1/8″-thick piece and season with salt and pepper.
Place 2 scallions on each piece of beef. Roll tightly and secure with toothpicks.
Combine sauce ingredients in a small pot and simmer for 4-5 minutes.
Coat roll-ups with sauce twice and cook for 2-3 minutes. Then pour remaining sauce in and cook until thickened.
Remove the toothpicks and slice each beef roll into bite-sized pieces. Enjoy!