In a large bowl, combine beef, ginger, garlic, soy sauce, sugar and mirin. Let marinate for 15 minutes.
Heat a cast iron skillet or wok on high. Add oil, then the beef mixture. Stir fry for about 3 minutes and transfer to a plate. On the same skillet, lower the heat to medium and add the bean sprout, scallions and some of the hot peppers. (You can use the whole hot peppers depending on how spicy you like). Add the cornstarch and return the beef to the skillet. Season with salt and pepper. Stir and cook fro 1 to 2 minutes then place on a serving platter, Serve
Recipe by The Gluten Free at https://www.theglutenfree.com/gluten-free-spicy-beef-with-bean-sprouts-and-scallions/