Season beef with soy sauce, ginger, garlic, mirin, brown sugar and a little bit of salt and pepper. Cover and marinate for 30 minutes.
In a small bowl, whisk together the water and cornstarch.
Roast shishito peppers until skin become blistered, set side.
Preheat a wok or a large cast iron pan until it starts to smoke. Add peanut oil then the beef. Cook for 2 minutes until brown. Add scallions and bean sprouts. Stir in the cornstarch mixture and cook for 2 minutes. Serve with roasted shishito peppers. Enjoy!
Recipe by The Gluten Free at https://www.theglutenfree.com/gluten-free-beef-with-bean-sprouts-and-scallions/