1 pound top sirloin steak or flank steak, cut into very thin strips
1/4 cup soy sauce (divided)
1/3 cup Shaoxing wine (divided)
2 tablespoons cornstarch
1/2 cup low-sodium chicken stock
1 tablespoon sesame oil
1 tablespoon sugar
1 teaspoon freshly ground black pepper
2 green bell peppers, cored and cut into 1-inch squares (about 2 cups)
1 red bell pepper, cored and cut into 1-inch squares (about 1 cup)
1 large onion, cut into 1-inch dice (about 1 1/2 cups)
2 medium cloves garlic, finely minced
2 teaspoons finely minced fresh ginger
3 scallions, whites only, finely minced
4 tablespoons vegetable, peanut, or canola oil
Kosher salt to taste
2-3 tablespoons Sriracha
Combine beef, 1 tablespoon soy sauce, and 1 tablespoon Shaoxing wine in a bowl and toss to coat. Let marinate for at least 20 minutes at room temperature or up to 3 hours in the refrigerator.
Combine remaining soy sauce with cornstarch and stir with a fork to form a slurry. Add remaining Shaoxing wine, chicken stock, sesame oil, sugar, and pepper. Set aside.
Combine peppers and onions in a bowl and set aside. Combine garlic, ginger, and scallions in a small bowl and set aside.
When ready to cook, heat 1 tablespoon oil in a wok or a large deep skillet over high heat until smoking. Add half of the beef and cook without moving until well seared, about 1 minute. Continue cooking while stirring and tossing until lightly cooked but still pink in spots, about 1 minute more. Transfer to a large bowl. Repeat with 1 more tablespoon of oil and remaining beef. Repeat with 1 more tablespoon oil and half of the peppers and onions. Transfer to the bowl with the beef. Repeat with remaining oil and remaining peppers/onions.
Return pan to high heat and add the peppers/onions/beef and the garlic/ginger/scallion mixture. Cook, tossing and stirring until incorporated about 30 seconds. Add sauce and cook, tossing and stirring constantly until thickened, about 45 seconds longer. If you like your Chinese recipes with spice add several tablespoons of Sriracha.
Carefully transfer to a serving platter and serve with rice