01 - Combine the beef slices with 1 tablespoon soy sauce and cornstarch in a medium bowl. Let marinate for 10 minutes.
02 - Whisk together the remaining soy sauce, sriracha, hoisin sauce, brown sugar, rice vinegar, garlic, ginger, and sesame oil in a small bowl.
03 - Heat a large skillet or wok over high heat with a splash of oil. Sear the beef in batches until browned and cooked through, about 2 to 3 minutes per batch, then set aside.
04 - In the same skillet, add more oil if necessary and stir-fry the bell pepper, snap peas, and carrot for 2 to 3 minutes until tender-crisp.
05 - Return the beef to the skillet and pour in the spicy sauce. Toss to coat evenly over high heat for 1 to 2 minutes until heated through.
06 - Serve the beef and vegetables over steamed rice. Garnish with sliced spring onions, toasted sesame seeds, and fresh cilantro if desired.