Thinly slice the flank steak against the grain into bite-sized strips.
In a small bowl, whisk together the tamari, honey, grated ginger, and minced garlic to create the stir-fry sauce.
Heat the sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the beef strips to the pan in a single layer and sear until browned, about 2 minutes per side, then remove and set aside.
Add the broccoli florets to the same pan with a tablespoon of water, cover, and steam for 3 minutes until tender-crisp.
Return the beef to the pan, pour the sauce over the mixture, and toss for 1-2 minutes until the sauce reduces and coats everything.
Season with sea salt, black pepper, and red pepper flakes, then garnish with toasted sesame seeds before serving.