In a small bowl, combine lemon juice, olive oil, minced garlic, salt, and pepper to create the marinade.
Place the 4 oz chicken breast in the marinade, ensuring it is well-coated. Allow it to marinate for at least 20 minutes.
Preheat the grill to medium-high heat. Grill the chicken breast for about 6-7 minutes per side or until the internal temperature reaches 165°F.
Meanwhile, prepare the quinoa according to package instructions, or heat the pre-cooked quinoa if using leftovers.
For the broccoli, preheat your oven to 425°F. Toss broccoli florets with a small drizzle of olive oil, salt, and pepper. Roast in the oven for about 15-20 minutes until tender and slightly crispy.
Assemble your plate by placing the cooked quinoa, roasted broccoli, and grilled chicken breast. Optionally, drizzle any remaining marinade over the top for added flavor.
Serve warm and enjoy your balanced, protein-packed meal.