Pat the flank steak dry with paper towels and slice across the grain into thin, bite-sized strips.
In a small bowl, whisk together the dried rosemary, dried thyme, sea salt, and black pepper.
Heat the olive oil in a large cast-iron skillet or heavy-bottomed pan over medium-high heat until shimmering.
Place the beef strips in the skillet in a single layer, ensuring they are not crowded, and sear for 2 minutes without moving them to develop a golden crust.
Add the minced garlic, broccoli florets, and sliced red bell pepper to the skillet.
Toss all ingredients together and continue to cook for 3-4 minutes, stirring frequently, until the vegetables reach a tender-crisp texture and the beef is fully cooked.
Remove from heat and serve immediately while hot and fragrant.