Thinly slice the sirloin steak against the grain into bite-sized strips and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, grated ginger, minced garlic, and red pepper flakes to create the stir-fry sauce.
Heat the avocado 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, cover, and steam for 2 minutes until tender-crisp.
Return the beef to the pan, pour in the sauce, and toss everything together for 1-2 minutes until the sauce thickens slightly and coats the ingredients.
Remove from heat, drizzle with toasted sesame oil, and garnish with sesame seeds before serving.