Heat olive oil in a large skillet over medium-high heat.
Add diced onion and cook for 3 minutes until translucent.
Add minced garlic and cook for 30 seconds until fragrant.
Add ground beef to the skillet and cook, breaking it apart with a spatula, until browned and cooked through, about 6-8 minutes.
While the beef cooks, steam broccoli florets until tender but still crisp, about 4 minutes.
Add sliced red bell pepper and julienned carrot to the skillet with the beef and cook for 3 minutes, stirring occasionally.
In a small bowl, whisk together soy sauce, oyster sauce, hoisin sauce, sesame oil, black pepper, and crushed red pepper flakes.
Pour the sauce mixture over the beef and vegetables in the skillet and stir well to combine. Cook for an additional 2 minutes to let the flavors meld.
To assemble the bowls, divide cooked quinoa and brown rice evenly among four bowls.
Top each bowl with the beef and vegetable mixture.
Garnish with sliced green onions and toasted sesame seeds.
Serve immediately and enjoy your high protein beef bowl.