In a bowl, mix together the soy sauce, honey, rice vinegar, sesame oil, and grated ginger. Stir until the honey dissolves. Add the sliced beef to the marinade and toss to coat. Let the beef marinate for 15-20 minutes.
Heat vegetable oil in a large skillet or wok over medium-high heat. Add bell peppers, carrots, and onion. Stir-fry for 3-4 minutes until vegetables are tender-crisp.
Push the vegetables to the side and add the marinated beef to the skillet. Stir-fry for 5-7 minutes until browned and cooked through.
Add minced garlic and red pepper flakes (optional) and stir-fry for another 1-2 minutes until fragrant. Garnish with green onions before serving.
Notes
You can customize this dish by adding different vegetables or adjusting the heat level to suit your taste. It's perfect for a quick weeknight dinner!