Coat the beef. Toss the sliced flank steak with cornstarch, salt, pepper, and Buttery Steakhouse seasoning until evenly coated.

Make the sauce. Whisk together soy sauce, brown sugar, ginger, garlic, warm water, and sesame oil in a bowl until the sugar dissolves. Set aside.

Sear the beef. Heat oil in a large skillet or wok over medium-high heat. Add the beef in a single layer and sear for 2 to 3 minutes per side until browned and slightly caramelized. Work in batches to avoid crowding. Remove and set aside.

Cook the broccoli. In the same pan, add the broccoli and cook for 3 to 4 minutes until tender-crisp.

Cook the noodles. Cook the ramen noodles according to package directions, discard the seasoning packets, drain, and set aside.

Build the dish. Return the beef to the pan with the broccoli. Pour the sauce over everything and toss to coat. Simmer for 2 to 3 minutes until the sauce thickens and clings to the beef. If you want a thicker sauce, stir 1 tbsp cornstarch with a splash of water and add it to the pan.

Add the noodles. Toss the cooked ramen noodles into the pan and mix everything together until the noodles are coated in the sauce.

Garnish and serve. Top with sliced green onions and sesame seeds. Serve immediately.