Gather all ingredients.

In a mixing bowl, combine the soy sauce, brown sugar, sesame oil, minced garlic, grated ginger, rice vinegar, and black pepper. Whisk until the sugar is dissolved.

Select your choice of beef, such as flank steak or sirloin. Cut it into thin slices against the grain.

Place the beef slices in a resealable plastic bag or shallow dish. Pour the marinade over the beef, ensuring it's fully coated.

Seal the bag or cover the dish and refrigerate for at least 30 minutes, or up to 4 hours for best results.

Preheat your grill or skillet over medium-high heat.

Remove the beef from the marinade and let excess drip off. Grill or sauté the beef for about 2-3 minutes per side until cooked to your desired doneness.

Let the beef rest for a few minutes before serving.

Serve hot over rice or in lettuce wraps.