In a medium saucepan, combine the rinsed quinoa and water. Bring to a boil over medium-high heat.
Reduce heat to low, cover, and simmer for 15 minutes or until quinoa is tender and water is absorbed.
Remove from heat and fluff quinoa with a fork. Set aside to cool slightly.
Heat vegetable oil in a large skillet or wok over medium-high heat.
Add ground beef and cook, breaking it apart with a spatula, until browned and cooked through, about 5 minutes.
Add chopped broccoli, minced garlic, and chopped onion to the skillet. Stir-fry for 3-4 minutes until broccoli is tender-crisp.
Push the beef and vegetables to one side of the skillet. Pour the beaten eggs into the empty side and scramble until fully cooked.
Add the cooked quinoa to the skillet and stir to combine all ingredients evenly.
Pour soy sauce, oyster sauce, and sesame oil over the mixture. Stir well to coat everything.
Season with ground black pepper and continue to cook for 2 more minutes, stirring frequently.
Remove from heat and garnish with sliced green onions before serving.