Brown beef (or pork). Remove from pan and drain excess grease (if necessary).
Heat sesame oil in pan until shimmering.
Cook onions until translucent, about 3 minutes.
Cook garlic and ginger until fragrant, about 30 seconds.
Add soy sauce, brown sugar and both vinegars.
In a small bowl, combine beef broth and cornstarch to make a slurry. Add the slurry to the pan, stirring constantly.
Put beef (or pork) back into the pan and simmer until thick and the flavors have melded, about 5 minutes.
Serve over rice and garnish with green onions, if desired.
You could also use shredded or leftover beef or pork (great way to use leftovers). Just start with step 2.You can use 2 teaspoons of dried and ground ginger instead. You can use siracha instead. This meal freezes great. Thaw and reheat or reheat from frozen with a little bit of water.