Heat the sesame oil in a large skillet over medium high heat.
Add the ground beef and the diced onion to the skillet. Cook the beef (breaking up the beef as it cooks) until the beef is no longer pink and the onions are tender (5-7 minutes). Drain off any excess grease.
In a separate bowl, whisk together the sauce ingredients. Pour this on top of the beef mixture in the skillet. Toss to coat the beef with the sauce.
Then cook for 1 minute on a low simmer to thicken the sauce.
Serve immediately while warm topped with the sesame seed and diced green onions. Enjoy!
Notes
Refrigerate the leftovers in an airtight container for up to 5 days. We love serving this mixture over rice.