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, coconut aminos, minced ginger, minced garlic, and arrowroot powder to create the stir-fry sauce.
Heat the toasted 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 to the same pan with a splash of water, covering for 2 minutes to steam-tenderize them.
Return the beef to the pan, pour in the sauce mixture, and toss constantly for 1 minute until the sauce thickens and coats everything beautifully.
In a separate small pan, quickly sauté the cauliflower rice until heated through and slightly softened.
Serve the beef and broccoli over the cauliflower rice and garnish with sesame seeds.