In a large skillet over medium heat, cook beef, breaking it up a little, but not too much. You want the chunks to be big to help give the sandwhich stability.
Cook until well browned, about 5-6 minutes. Then add garlic, sesame oil, ketchup, hoisin, water, soy sauce, rice wine vinegar, and sriracha. Stir everything together with the beef.
Cook on medium heat for about 5-6 minutes, until mixture thickens and becomes "sloppy".
Toast the buns (optional) and spoon the beef mixture on to buns, then top with green onions.
Enjoy!
