Thinly slice the flank steak against the grain into bite-sized strips and season with sea salt and black pepper.
In a small bowl, whisk together the tamari, honey, minced ginger, minced garlic, and arrowroot powder until smooth.
Heat the sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips in a single layer and sear for 2-3 minutes until browned and caramelized, then remove from the pan and set aside.
Add the broccoli florets and sliced red bell pepper to the same pan with a splash of water, covering for 2 minutes to steam-tenderize.
Return the beef to the pan and pour the sauce over the mixture, tossing constantly for 1 minute until the glaze thickens and coats everything evenly.
Garnish with sesame seeds and serve immediately while hot.