Whisk together beef broth and cornstarch in a small bowl until smooth.
Heat 1 tbsp olive oil in a large skillet (cast iron if you have it) over high. Add steak, cook, stirring occasionally, until browned, about 2-3 minutes. Add 1.5 tbsp tamari and 1 tsp coconut sugar. Cook, stirring often, until meat is charred, 1-2 minutes. Remove steak to a plate.
Add cabbage, ginger, garlic, and remaining 1 tbsp oil. Cook, stirring often until cabbage begins to wilt, 2-3 minutes. Add stock mixture, remaining tamari, and remaining coconut sugar. Bring to a boil, then reduce heat to medium, and simmer until cabbage is crisp-tender, about 2 minutes.
Stir in steak, carrots, scallions, sesame oil, and vinegar. Cook 1 minute.
Sprinkle with sesame seeds. Serve with your favorite starch, like brown rice!