In a bowl, toss the sliced flank steak with cornstarch until well coated. Set aside for 10 minutes to allow the cornstarch to adhere.

In a small bowl, whisk together soy sauce, honey, rice vinegar, garlic, and ginger. Set aside.

Cook the egg noodles according to package instructions. Drain and set aside.

In a large skillet or wok, heat vegetable oil over medium-high heat. Add the beef in a single layer and cook until crispy and browned, about 3-4 minutes per side. You may need to do this in batches to avoid overcrowding the pan.

Once the beef is cooked, reduce the heat to medium and pour the sauce over the beef. Stir to coat and cook for an additional 2-3 minutes until the sauce thickens slightly.

Add the cooked noodles to the skillet and toss to combine with the beef and sauce. Cook for another minute to heat through.

Serve immediately, garnished with sliced green onions and sesame seeds if desired.