Pour sesame oil into a cold skillet or wok, turn up to medium-high, and swirl it around so the bottom is covered once hot.
Add the ground beef after your pan is good and hot. Use your spatula to break it up and keep flipping until all the meat’s browned nicely. Scoop out extra grease if you like things leaner.
Toss in the chopped garlic and grated ginger with the beef. Keep stirring for about a minute so those smells really come out.
Scatter in the cabbage and carrot. Cook, tossing for 4 or 5 minutes, so they get a little soft but still stay pretty crisp.
Drizzle in your soy sauce, rice vinegar, plus oyster sauce now, and toss well so everything gets coated and the flavors blend nicely.
Drop in your cornstarch-water mix, stir everything well for a minute or two till the sauce looks glossy and clings to the meat and veggies. Dash in the red pepper flakes for some kick.
Serve over rice or noodles.
