Heat the olive oil in a large skillet over medium-high heat.
Add the diced onion and minced garlic to the skillet and sauté for 2-3 minutes until fragrant and translucent.
Add the ground beef to the skillet and cook, breaking it apart with a spatula, until browned and cooked through, about 6-8 minutes.
Drain any excess fat from the skillet.
Add the sliced red and green bell peppers, broccoli florets, and snap peas to the skillet. Stir well to combine.
Cook the vegetables with the beef for 5-6 minutes until they are tender-crisp.
Stir in the soy sauce, Worcestershire sauce, ground black pepper, salt, and crushed red pepper flakes. Mix thoroughly to coat the beef and vegetables evenly.
Cook for an additional 1-2 minutes to allow the flavors to meld.
Remove from heat and sprinkle the chopped fresh parsley over the stir-fry.
Serve hot as a high-protein main dish.