In a bowl, combine the soy sauce, oyster sauce, hoisin sauce, brown sugar, minced garlic, minced ginger, and cornstarch. Add the thinly sliced flank steak to the bowl and toss to coat.

Let marinate for at least 15 minutes.

Heat 1 tablespoon of vegetable oil in a large skillet or wok over high heat. Add the marinated beef to the skillet in a single layer and cook, stirring occasionally, until browned and cooked through, about 3-4 minutes. Remove the beef from the skillet and set aside.

In the same skillet, heat the remaining tablespoon of vegetable oil. Add the snow peas and cook, stirring constantly, until they are bright green and slightly tender, about 2-3 minutes.

Return the cooked beef to the skillet with the snow peas and stir to combine. Cook for an additional 1-2 minutes to heat everything through.

Serve the Asian beef and snow peas over cooked rice, garnished with sesame seeds and sliced green onions if desired.