Combine the soy sauce, rice vinegar, sriracha, and brown sugar in a small bowl. Stir until the sugar is mostly dissolved and everything is well blended. Set the sauce aside while preparing the beef.
Heat the oil in a large skillet over high heat. Add the ground beef and cook while breaking it apart with a spoon. Continue cooking until no pink meat remains and the beef starts to develop some color.
Stir in the minced garlic and red pepper flakes. Cook for about one minute, allowing the garlic to become fragrant. This step helps build the spicy foundation of the dish.
Add the prepared firecracker sauce to the skillet. Stir well so every piece of beef is coated. The mixture will become glossy and aromatic almost immediately.
Continue cooking over high heat for several minutes. Allow the sauce to reduce and cling to the meat. The caramelization creates deeper flavor and gives the beef its signature firecracker taste.
Pour in the water and stir well. This loosens the caramelized sauce slightly and creates a more succulent texture. Cook for another minute until everything is evenly coated.
Transfer the beef over warm rice or noodles. Finish with sliced green onions, sesame seeds, and your favorite fresh vegetables. Serve immediately while hot.