Thinly slice the flank steak against the grain into bite-sized strips to ensure maximum tenderness.
In a small bowl, whisk together the coconut aminos, toasted sesame oil, and arrowroot powder until smooth.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the beef strips to the skillet in a single layer, season with salt and pepper, and sear for 2 minutes until browned.
Toss in the broccoli florets, minced garlic, and grated ginger, then stir-fry for an additional 3 to 4 minutes until the broccoli is bright green.
Pour the prepared sauce over the beef and vegetables, tossing constantly for 1 minute until the glaze thickens and coats everything beautifully.
Transfer to a plate and garnish with sesame seeds before serving immediately.