Begin by slicing your flank steak or sirloin thinly against the grain, ensuring each piece is about ¼ inch thick for maximum tenderness.

In a medium bowl, combine freshly grated ginger, soy sauce, brown sugar, minced garlic, and chili flakes. Whisk together until the sugar dissolves.

Heat a large wok or skillet over medium-high heat with a splash of cooking oil. Add the sliced beef in a single layer and sear for about 4-5 minutes until browned.

In the same pan, add more oil if needed and toss in the chopped bell peppers and broccoli. Stir-fry for about 3-4 minutes until tender-crisp.

Return the cooked beef to the pan and pour in the prepared sauce. Stir to combine and cook for an additional 2-3 minutes to heat through.

Serve immediately over rice, noodles, or on its own, garnished with fresh herbs or sesame seeds.