Slice the flank steak against the grain into very thin strips to ensure maximum tenderness.
Heat the toasted 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, approximately 2-3 minutes, then remove and set aside.
In the same pan, add the broccoli florets, sliced bell peppers, and sugar snap peas, sautéing for 3-4 minutes until tender-crisp.
Stir in the minced garlic and freshly grated ginger, cooking for 1 minute until the aromatics are fragrant.
Return the seared beef and any accumulated juices to the pan.
Pour the coconut aminos over the mixture and toss everything together for 1-2 minutes until the sauce coats the ingredients.
Season with sea salt and black pepper to taste.
Transfer to a plate and garnish with sesame seeds before serving hot.