Heat olive oil in a large skillet over medium-high heat.
Add diced onion and minced garlic to the skillet and sauté for 2-3 minutes until fragrant and translucent.
Add ground beef to the skillet. Cook, breaking it up with a spatula, until browned and cooked through, about 5-7 minutes.
Drain excess fat from the skillet if necessary.
Add diced red bell pepper, zucchini, broccoli florets, and sliced carrot to the skillet. Stir well to combine.
Cook the vegetables with the beef for 5-7 minutes, stirring occasionally, until the vegetables are tender but still crisp.
In a small bowl, whisk together soy sauce, tomato paste, black pepper, salt, dried oregano, and crushed red pepper flakes.
Pour the sauce mixture over the beef and vegetables in the skillet. Stir well to coat everything evenly.
Cook for an additional 2 minutes to allow the flavors to meld.
Remove from heat and garnish with sliced green onions and chopped fresh parsley.
Serve hot on its own or over cooked rice or noodles if desired.