Heat the olive oil in a large skillet or wok over medium-high heat.
Add the diced onion and minced garlic to the pan, sautéing for about 2 minutes until they become fragrant and translucent.
Add the lean ground beef to the skillet, breaking it apart with a wooden spoon. Cook for 5-7 minutes until browned and cooked through.
Stir in the broccoli, bell pepper, and carrot. Cook for an additional 3-4 minutes, until the vegetables are tender-crisp.
Add the soy sauce, minced ginger, and red chili flakes (if using). Season with salt and pepper to taste. Stir well to combine and cook for another 2 minutes.
Remove from heat and serve the stir-fry over cooked brown rice or quinoa.
For added nutrition, consider incorporating other vegetables such as snap peas, zucchini, or baby corn.
To make this dish even healthier, consider using ground turkey or chicken as a substitute for ground beef.
Feel free to adjust the seasonings based on your taste preference; try adding sesame oil for a different flavor profile.