Slice the flank steak against the grain into thin, bite-sized strips.
In a small jar, whisk together the tamari, toasted sesame oil, honey, minced ginger, and minced garlic.
In a separate small bowl, stir the arrowroot powder and water together until smooth to create a slurry.
Heat 1 teaspoon of avocado oil in a large skillet or wok over medium-high heat, add the broccoli florets and a splash of water, then cover and steam for 3 minutes.
Remove the broccoli from the pan and set aside, then wipe the pan dry and add the remaining 1 teaspoon of avocado oil over high heat.
Sear the beef strips in a single layer for 2-3 minutes until deeply browned and just cooked through.
Return the broccoli to the pan, pour in the tamari sauce and the arrowroot slurry, and toss constantly for 1 minute until the sauce becomes thick and glossy.
Transfer to a plate and garnish with sesame seeds and red pepper flakes.